DCB F 34/ WHY

[Wright Brothers]

1st I'd like to thank the RDP community for all the professional hard hitting knowledge that comes out of this forum site.
I recently had a chat with AzGeo on this F34 Hip Hop artist of a boat that I spent most of my wife's money on. Like back in the day I just didn't do all my homework. George said to throw a tread out and let's discuss this F34 bottom and some ways that I could make this a more pleasurable beast. I've owned eliminator boats in the past and I came across this F34 with 2x1100 hp engines with 400 turbo trans and no#6 drives. I'm thinking now this is in my price range and HP matches the drivetrain (finally), it's longer and cooler. But little did I know that 82mph to about 115mph this thing is like Asian Carp jumping out the water. 112mph to 133mph it airs out smooth as glass and then you let off and go back through it. I though I had a fast boat but I think it's people just backing off and getting the heck out of my way. Lol. We run a 40 foot roadster in Florida poker runs and the normal speeds that we run are rite in my boats dance act. I need to make this boat SAFE! And safe for my family and friends. I'm going to try and put some pics out and any input would be greatly appreciated.

 

[Wright Brothers]

1st I'd like to thank the RDP community for all the professional hard hitting knowledge that comes out of this forum site.
I recently had a chat with AzGeo on this F34 Hip Hop artist of a boat that I spent most of my wife's money on. Like back in the day I just didn't do all my homework. George said to throw a tread out and let's discuss this F34 bottom and some ways that I could make this a more pleasurable beast. I've owned eliminator boats in the past and I came across this F34 with 2x1100 hp engines with 400 turbo trans and no#6 drives. I'm thinking now this is in my price range and HP matches the drivetrain (finally), it's longer and cooler. But little did I know that 82mph to about 115mph this thing is like Asian Carp jumping out the water. 112mph to 133mph it airs out smooth as glass and then you let off and go back through it. I though I had a fast boat but I think it's people just backing off and getting the heck out of my way. Lol. We run a 40 foot roadster in Florida poker runs and the normal speeds that we run are rite in my boats dance act. I need to make this boat SAFE! And safe for my family and friends. I'm going to try and put some pics out and any input would be greatly appreciated.

More pic F34

 

[AzGeo]

we all may learn something here .

Does it have any strakes on the rear portion of the sponsons ?

I see they tried to 'extend' the sponsons with the plates, but they too seem to have no 'strake' in their centers, but only a 'lip' out their outer edges .

Also wondering why they have a 'center moving plate' that has a cutout in it . IF the plate is effective in size and position, WHY the cut out ?

 

[hallett21]

Post this in the lounge. Also search for another f34 thread. Someone is kinda where you're at but I believe he made a lot of progress. Can't remember his screen name

 

[JD D05]

Yes there is a guy that has done through this on here.

 

[ONE-A-DAY]

The f34 was known for its problematic handling issues, most went back to dcb to try and get the bottom dialed in, some people just gave up, and some crashed. All in all there were only a handful made most likely because of the above. It's doable but it would be best to call dcb and let them tell you or possibly they can put you in touch with another owner. Otherwise there will be hundreds of suggestions and you may end up wasting a lot of time and money on failed experiments. I've owned several DCB's and Dave or Tony there are always glad to help regardless if you bought it new from them or not.

 

[ONE-A-DAY]

Google "dcb f34 handling issues" and lots of forum threads will come up. The common theme was that the early ones had issues and the later ones were ok, and many old ones were sent back to dcb to have the bottom design corrected. I'm not sure if the bill for that was on dave or not or on the customer.

 

[River Runnin]

Looks like you could use a set of real trim tabs on that bad boy! ...Solid..6" deeper and another 6" wider!....like the BXT here!..>>http://www.bennetttrimtabs.com/premier-hydraulic-trim-tab-systems/

...And these don't look bad either! http://www.lencomarine.com/index.php/products/trim-tabs/extreme-duty-performance

 

[Wright Brothers]

we all may learn something here .

Does it have any strakes on the rear portion of the sponsons ?

I see they tried to 'extend' the sponsons with the plates, but they too seem to have no 'strake' in their centers, but only a 'lip' out their outer edges .

Also wondering why they have a 'center moving plate' that has a cutout in it . IF the plate is effective in size and position, WHY the cut out ?

There's no strakes on the last roughly 6 feet of the boat. And the original owner said DCB cut that V out of the center plate. I think I spoke with Jeff from DCB and he said to switch the props to a radical rake,, 21 degree rake 16 1/4 diameter 37 pytch. He said it would not completely stop the issues but it would make the boat be way way better all around. The issue is I don't have 10k sitting around to throw at a set of props. Currently running a 16 1/8 X 37 pitch X 16 degree rake 5 blades.

 

[Wright Brothers]

Looks like you could use a set of real trim tabs on that bad boy! ...Solid..6" deeper and another 6" wider!....like the BXT here!..>>http://www.bennetttrimtabs.com/premier-hydraulic-trim-tab-systems/

...And these don't look bad either! http://www.lencomarine.com/index.php/products/trim-tabs/extreme-duty-performance

Thanks for that info. We talked some about tabs like that. I haven't seen a whole bunch of these f34s in any pictures to compare mine to.

 

[Wright Brothers]

The f34 was known for its problematic handling issues, most went back to dcb to try and get the bottom dialed in, some people just gave up, and some crashed. All in all there were only a handful made most likely because of the above. It's doable but it would be best to call dcb and let them tell you or possibly they can put you in touch with another owner. Otherwise there will be hundreds of suggestions and you may end up wasting a lot of time and money on failed experiments. I've owned several DCB's and Dave or Tony there are always glad to help regardless if you bought it new from them or not.

Tony mentioned switching props to a 21 degree rake for more now lift. He said it wouldn't clear the issue up but it would be a whole different boat with the prop swap. 10k for props, kinda strapped on that change rite now. And the old owner said he remembers trying a prop like that and said it didn't help.

 

[Wright Brothers]

we all may learn something here .

Does it have any strakes on the rear portion of the sponsons ?

I see they tried to 'extend' the sponsons with the plates, but they too seem to have no 'strake' in their centers, but only a 'lip' out their outer edges .

Also wondering why they have a 'center moving plate' that has a cutout in it . IF the plate is effective in size and position, WHY the cut out ?

No strakes from the last step back. Flat. The old owner said DCB cut that V out of the tab???

 

[Wright Brothers]

The f34 was known for its problematic handling issues, most went back to dcb to try and get the bottom dialed in, some people just gave up, and some crashed. All in all there were only a handful made most likely because of the above. It's doable but it would be best to call dcb and let them tell you or possibly they can put you in touch with another owner. Otherwise there will be hundreds of suggestions and you may end up wasting a lot of time and money on failed experiments. I've owned several DCB's and Dave or Tony there are always glad to help regardless if you bought it new from them or not.

Thank you for that. It's a cool looking boat, it's ah shame it behaves like it does. I have to be careful with passengers because it really hops. And the nose roll is really bad. Tony mentioned props, I might have to search the earth to try a set before I buy them. Thank you.

 

[AzGeo]

Eliminator 33's, way back . I feel that the 'leverage point' of the props so far behind the transom, with NO strakes on the rear portion 'lifting' it up, is the problem .

Where the strakes end on the bottom of the second step, that is the area that is 'lifting', and at lower speeds the center pud is also touching .

You get up to that 'magic speed', and the rear of the sponsons (with no strakes) won't LIFT the tail of the boat/leverage, so it BOUNCES on and off of the center pod . This causes the bow to go up and down 4' to 6', all the way up to where the 'high X dimension' can then run the boat FLAT only while the power is being applied . As soon as you begin to reduce throttle (slow down) the tail settles and starts to bounce all over again .

With drives up against the transom (props close in, Bravo style) the leverage point is AT the TRANSOM and lifts it 'quickly thru' that bouncing by being trimmed level or down, then 'trimmed up very slowly to allow the gross weight to 'rock' on the sponsons with strakes . (only way to carry the load)

As someone else here asked WHY his boat ran 'smooth and turned great', while not having those 'rear strakes . He has props that create the 'lift' and prevent the 'bounce', but that also allows the boat to run 'flat and wet', which would also allow 'good stable turning' .

The boat will run with different props, and you would be able to 'learn what it likes at speeds', but I prefer to 'lift' the entire mass UP, and then hold the maximum amount of air in the tunnels .

 

[Wright Brothers]

Eliminator 33's, way back . I feel that the 'leverage point' of the props so far behind the transom, with NO strakes on the rear portion 'lifting' it up, is the problem .

Where the strakes end on the bottom of the second step, that is the area that is 'lifting', and at lower speeds the center pud is also touching .

You get up to that 'magic speed', and the rear of the sponsons (with no strakes) won't LIFT the tail of the boat/leverage, so it BOUNCES on and off of the center pod . This causes the bow to go up and down 4' to 6', all the way up to where the 'high X dimension' can then run the boat FLAT only while the power is being applied . As soon as you begin to reduce throttle (slow down) the tail settles and starts to bounce all over again .

With drives up against the transom (props close in, Bravo style) the leverage point is AT the TRANSOM and lifts it 'quickly thru' that bouncing by being trimmed level or down, then 'trimmed up very slowly to allow the gross weight to 'rock' on the sponsons with strakes . (only way to carry the load)

As someone else here asked WHY his boat ran 'smooth and turned great', while not having those 'rear strakes . He has props that create the 'lift' and prevent the 'bounce', but that also allows the boat to run 'flat and wet', which would also allow 'good stable turning' .

The boat will run with different props, and you would be able to 'learn what it likes at speeds', but I prefer to 'lift' the entire mass UP, and then hold the maximum amount of air in the tunnels .

Is it possibly to add strakes now? There's a shop in Ohio that does custom bottom work and a friend of mine said this guy use to work for Skater? I'm not sure who it is but I wouldn't think it sounded like this guy could do this job. I'd like to know if he's familiar with this f34 bottom issue. I wonder why DCB would not want to correct any issue like this. If strakes would help it. My stinking aluminum row boat has freaking strakes all the way to the back. Gees.

 

[Flying_Lavey]

I am in no means an expert but to throw out my 2 cents..... what if you tried raising those hull extension tabs to essentially allow the hull to get a better attack angle and pack more air at slower speeds? AZGeo should have good thoughts if that is a good or bad idea. Just my 2 cents looking at them they look either completely parallel to the bottom or even slightly angled down.

 

[Wright Brothers]

I am in no means an expert but to throw out my 2 cents..... what if you tried raising those hull extension tabs to essentially allow the hull to get a better attack angle and pack more air at slower speeds? AZGeo should have good thoughts if that is a good or bad idea. Just my 2 cents looking at them they look either completely parallel to the bottom or even slightly angled down.

Thanks for that idea. I've had friends of mine say to take those things off. The original owner said it's even worse. He said the extensions at least let the boat ride nice all the way to the 80mph mark. I checked them and it seems they are completely parallel to the bottom. I guy that owned the boat is 76 and I kinda let myself believe that at his age he just didn't want to go over 80. He pulled a sales move out on me. I should have said if your nit going to hammer down on this at least 1time I should have just walked away.

 

[Flying_Lavey]

Thanks for that idea. I've had friends of mine say to take those things off. The original owner said it's even worse. He said the extensions at least let the boat ride nice all the way to the 80mph mark. I checked them and it seems they are completely parallel to the bottom. I guy that owned the boat is 76 and I kinda let myself believe that at his age he just didn't want to go over 80. He pulled a sales move out on me. I should have said if your nit going to hammer down on this at least 1time I should have just walked away.

Yeah, I wouldn't take them off. I would try to raise them though. Maybe even put them on a hydraulic or electric ram system so they essentially become adjustable cavitation plates.

 

[AzGeo]

those plates just make the 'V' section of the sponsons longer, which is more drag, but also a little more surface area (longer keels), but with more drag than lift .

Let's try this !

IF those plates and their rigging ARE STRONG ENOUGH, mill out a couple of 'aluminum strakes' at about a "1 degree angle down" from the 'V' deadrise of the sponsons .

So you would (drill and bolt) a couple of aluminum wedges, to the bottoms of each plate .

Mount the 'thin side' about 4" up from the lowest edge of the sponson keels . The aluminum should be about 3 1/2" to 4 1/2" wide, and as long as the plate's bottom surface . Shape them with a VERY SHALLOW ENTRY CURVE . (like adding strakes to the plates)

So if the deadrise is 16 degrees, you want 17/18 degrees of aluminum wedge .

This should give 'tremendous lift' where this hull has never had any .

This 'cheap/easy TEST', will not cure the problem 25%, but it will show the kind of effect, adding strakes to the hull bottom, will do .

MAKE NO OTHER CHANGES ! Water test the boat .............

 

[Wright Brothers]

those plates just make the 'V' section of the sponsons longer, which is more drag, but also a little more surface area (longer keels), but with more drag than lift .

Let's try this !

IF those plates and their rigging ARE STRONG ENOUGH, mill out a couple of 'aluminum strakes' at about a "1 degree angle down" from the 'V' deadrise of the sponsons .

So you would (drill and bolt) a couple of aluminum wedges, to the bottoms of each plate .

Mount the 'thin side' about 4" up from the lowest edge of the sponson keels . The aluminum should be about 3 1/2" to 4 1/2" wide, and as long as the plate's bottom surface . Shape them with a VERY SHALLOW ENTRY CURVE . (like adding strakes to the plates)

So if the deadrise is 16 degrees, you want 17/18 degrees of aluminum wedge .

This should give 'tremendous lift' where this hull has never had any .

This 'cheap/easy TEST', will not cure the problem 25%, but it will show the kind of effect, adding strakes to the hull bottom, will do .

MAKE NO OTHER CHANGES ! Water test the boat .............

That sounds really good. I was wondering if that could be done on that whole flat surface on the last 6 ft of the bottom? But I will try the plates 1st to see what that does and go from there. I won't get to water test 2.5 months because of the weather.

 

[AzGeo]

it should have strakes under the last 6' of sponsons, but I'm just offering options to gaining the knowledge, rather than just 'blind faith' ............

 

[Wright Brothers]

it should have strakes under the last 6' of sponsons, but I'm just offering options to gaining the knowledge, rather than just 'blind faith' ............

What do you mean by the V section of the sponsons? And I do remember someone mentioned limiting the down movement of the center tab? Should I lock that thing in neutral position? I do use it. I have to.

 

[AzGeo]

the left and right sponsons have 'deadrise' which is the angle they are compared to vertical or horizontal (the water surface) .

I'm talking about the black plates on the ends of both sponsons . If their mountings and their movement equipment are STRONG ENOUGH, put the 'aluminum strakes' on the bottom of them .

Once you get the boat to run correctly, you can then look at doing something in the center, and it sure as hell ain't anything like that red POS .........

When using a 'moving center plate', it needs to be 'all the way across' and then you will also need 'tunnel side curtains', to keep the PACKED AIR off the props . This stuff is way down the line .....

 

[Wright Brothers]

the left and right sponsons have 'deadrise' which is the angle they are compared to vertical or horizontal (the water surface) .

I'm talking about the black plates on the ends of both sponsons . If their mountings and their movement equipment are STRONG ENOUGH, put the 'aluminum strakes' on the bottom of them .

Once you get the boat to run correctly, you can then look at doing something in the center, and it sure as hell ain't anything like that red POS .........

When using a 'moving center plate', it needs to be 'all the way across' and then you will also need 'tunnel side curtains', to keep the PACKED AIR off the props . This stuff is way down the line .....

I think the extension plates will hold the strakes. So that will be my plan of attack. 1st I have a dead engine and I'm almost ready to hit the dyno and when that's done I will get on the strakes. I can't wait to try this. The guy I bought the boat from said the props made transom lift because he felt the boat had enough bow lift. And he also said he sent the boat back to DCB and they worked on the under side of the tunnel mid way?? He couldn't remember what they did.

 

[JRider]

If you have 1.24 drives you will still be able to run 147 with these. If I thought I could pull them I would have bought them already.

http://www.offshoreonly.com/classifieds/hering-props-o68138.html

I have 16.5" x 32 x 15* rake 4 blades, also 16.5"x 33 x 15* (maybe 16*?) rake 5 blades. The 4 blades run a whole lot better than the 5s. My theory is that the low rake 5 blades have too much lift at the transom, and only at the transom.

I understand AzGeos theory/theories and really appreciate his input, although some information I have may counter the center pod theory. So a member on here named Gordy has/had an F34 that did not have a center pod and it had the same porpoise issue, and it was not even a #6 boat, he was running SCXs on boxes I believe. He ended up taking a lot of weight out it by cutting out the bow to make it a walk through open bow. After he did this his porpoise was totally gone. BTW the bravo boats were supposed to be better than the #6 boats. I am sure the open bow also affected the air flow over the deck, could be a component that helped. To me it just seems like I just cant quite carry the bow, that is something the 20* or 21* rake 5 blades would definitely help. Teague is the guy who spent a ton of time dialing one of these in, he did a lot of prop testing and ended up with the high rake 5 blades.

The first thing I am going to try this year is to take weight out of the bow, there are built in subs up there glassed in right from DCB, going to pull the speakers out and the interior panels over them, going to pull the amps and mount board out, as well as the huge sleeping pad. If the boat gets better I may just cut out the glassed in boxes out. Going with all JL 8.8s anyway and dont even need subs. I am curious if strakes would help in the first step, or possibly filling in the first step, I think it was Azgeo that said they did that on some 33 eliminators. I think he mentioned something about it is not a good idea to have the steps even with each other.

Let me be clear that my boat isnt that bad, I only really had a slight hop in perfectly calm water. It didnt even do it with any kind of chop. I have talked with Mr Wright on the phone and makes it sound as if his is porpoise is violent. Keep in mind that our hulls are also different, his tunnels are deeper than mine. Not sure if it is good or bad.

 

[AzGeo]

did the 'boxes' have more 'tuck under angle' on them ? That would change the 'leverage' a lot .

I don't see how reducing 'bow weight' will help 'lift the tail' . If bow weight were an answer, it would be to 'add weight' to the bow, counteracting the 'dragging tail' . (one of the 33 Daytonas tried adding bow weight and it slowed the bounce)

The boat with no center pod, would have even 'less air entrapment', unless the tunnel 'roof' had been reduced . This also shows me that; "it's all about LIFTING the gross weight, and not an air trap problem at 80 MPH" .

I would also add that a hull 'with NO center pod' would have the highest 'X' dimensions of all . It also does not have strakes to the rear ?

The Eliminators I measured (early 33's) had all the 'steps' in line . You could put a straight edge from the 'notch' forward to the front most step, and that edge would TOUCH the trailing edge of all the steps .

I'm ready to learn ..........

 

[JRider]

did the 'boxes' have more 'tuck under angle' on them ? That would change the 'leverage' a lot .

I don't see how reducing 'bow weight' will help 'lift the tail' . If bow weight were an answer, it would be to 'add weight' to the bow, counteracting the 'dragging tail' . (one of the 33 Daytonas tried adding bow weight and it slowed the bounce)

The boat with no center pod, would have even 'less air entrapment', unless the tunnel 'roof' had been reduced . This also shows me that; "it's all about LIFTING the gross weight, and not an air trap problem at 80 MPH" .

I would also add that a hull 'with NO center pod' would have the highest 'X' dimensions of all . It also does not have strakes to the rear ?

The Eliminators I measured (early 33's) had all the 'steps' in line . You could put a straight edge from the 'notch' forward to the front most step, and that edge would TOUCH the trailing edge of all the steps .

I'm ready to learn ..........

I cant answer the question on the boxes, I just dont know that. As far as the weight I see what you are saying. I am saying somewhat of the opposite, I tried low rake 5 blades which give the boat lift at the transom...it made the boat worse. The 4 blades do not lift the transom as much as the 5 blades and the boat ran much better. Teague found the same thing, by using a HIGH rake 5 blade that gives more bow lift. This is why I am not totally convinced it needs lift from strakes in the rear.

 

[toyaddiction]

Those back plates look dangerous to me. Especially if your going to run offshore. What happens when you jump and land off a swell and one of them breaks off. It also has to screw up the X dimension and how the water is fed to the props. I had a similar problem when I purchased my 36 Daytona. Someone thought it would be a good idea to put a larger plate on the tunnel tab. I took it off and gained 30 mph and the boat handled 100% better. The 36 Daytona's all porpoise on flat water between 85 and 105. They just cannot carry the bow at those speeds. Throw in a head wind and some chop and they are great

The 33 Daytona's also porpoise but they added a wedge on the outside of the rear of the tunnel. That helped a lot. My 33 has an open bow and a wedge so I am running a 21 rake to carry the bow. I have no porpoise at all. I would think that the open bow 34 had a lot more weight added to the front so it rides flat now.

I would take off the back plates and purchase or borrow some props. Then remove as much weight as possible from the front of the boat. It is my understanding that the tunnel tab should only be used to get on plane. After that it needs to be clear of the water.

Just my 2 cents from my experience

 

[TEAGUE CUSTOM MARINE]

Your first and most glaring issue is that you have the wrong props. This boat needs 21 degree rake propellers. Even 18's wouldn't be quite right but with 16's I'm sure it is horrible.

With the props turning IN (towards each other) more rake provides more nose lift, which helps the tunnel compression get the boat flying earlier. It is not like trimming the boat up with lower take props, it's a different effect. Too much rake turning in will make the boat nose flighty at top speed, even with negative trim. F34's don't have that issue.

DO NOT try to become an Internet bottom theory expert. DCB knows what to do with these bottoms to help the transition, the first generation bottom was almost more dangerous slowing down through the hop, probably the reason a few F34's have swapped ends. Not all of these incidents were public knowledge.

Also, you say "400 turbo" transmissions. Can you take a pic of this? The motors could be too far forward. Moving the engines even 2 inches in the boat effects COG dramatically. They are the heaviest objects bolted into the boat by far, even with a full fuel load.

I'll look if we have any high rake props that would be sellable...

JT

 

[JRider]

I would be interested in props in the 30 to 33 range

 

[JRider]

 

[JRider]

 

[TEAGUE CUSTOM MARINE]

Wow that's unique. Not many turbo 400's in #6 applications, if any at all. Do they direct couple or is there a small driveline? Maybe take a measurement from the rear motor plate to transom at crankshaft CL... Anyways I know you aren't trying to spend a lot of money and changing the transmissions and driveline configuration will cost more than new props. Conclusion: find some props.

We don't have any 21 deg props on the shelf. If you have to buy some used from someone, I can tell you this is the direction you need to go, for sure. Also, it will be easier to find props 16.5 diameter and 34-37 pitch in a high rake for a catamaran. It is better to run a shorter gear ratio and taller prop. The boat should probably have a 1.35 gear.

Side note: running "tunnel tab" at a slight down angle will increase tunnel compression and lift the whole boat while at speed. This can make the rear end feel slippery. It should be used only to eliminate a small porpoise due to glassy water. It cannot cure bad setup, in fact using it could crash the boat if the rest of the setup is not at least decent and if you don't already know how to use it. The tab can help in certain conditions say 70-80 in smooth water, but if you leave it down and accelerate to 120 you might end up taking a swim. Advanced users only.

Also, adding strakes to the rear running surface will increase sponson lift REAR of CG, reduce the angle of attack of the tunnel, reduce the engagement of the prop and skeg with the water, and generally make this issue Worse.

JT

 

[Wright Brothers]

Your first and most glaring issue is that you have the wrong props. This boat needs 21 degree rake propellers. Even 18's wouldn't be quite right but with 16's I'm sure it is horrible.

With the props turning IN (towards each other) more rake provides more nose lift, which helps the tunnel compression get the boat flying earlier. It is not like trimming the boat up with lower take props, it's a different effect. Too much rake turning in will make the boat nose flighty at top speed, even with negative trim. F34's don't have that issue.

DO NOT try to become an Internet bottom theory expert. DCB knows what to do with these bottoms to help the transition, the first generation bottom was almost more dangerous slowing down through the hop, probably the reason a few F34's have swapped ends. Not all of these incidents were public knowledge.

Also, you say "400 turbo" transmissions. Can you take a pic of this? The motors could be too far forward. Moving the engines even 2 inches in the boat effects COG dramatically. They are the heaviest objects bolted into the boat by far, even with a full fuel load.

I'll look if we have any high rake props that would be sellable...

JT

Thanks for jumping in here. I think I spoke with Tony at DCB and he mentioned you in regards to having a really good outcome on a F34 project. Tony said swap the props and I wouldn't believe the difference. But he did say that it would be almost impossible to try a set through a prop program because they don't stock that, it would have to be made. I just can't swing that money rite at the moment. The original owner said he worked with Dave and he had seen the extension plates on the bottom and said they were fine. I don't know what was done but the boat at sometime went back and forth a couple time to DCB for something fiberglass related work on the underside trying to remedy the problem???? I will get some pics and measurements of the engine and trans placement Saturday and post them. The original owner said he thought there's to much bow lift now? He told me to get some sand bags,(free) and drag them around the boat, 1st to the nose and see if it helped. Do as much low buck testing as possible before buying props. Because he (thought) when he ordered the boat he did the prop program and tried a set he (thought) that were pretty close to the 21 rake and felt no change. Like George mentioned the strakes on the bottom to help air this thing out some. I've looked at all the bottoms of the big cats and the strake goes all the way to the back. Is there no reason for that on smaller center pod cats? I'm tried of racket strapping my wife in the passenger seat so she doesn't pop out and I'm almost out of friends that will ride with me because of this. Lol. Thank you JT, I consider this an honor talking with you.

 

[Wright Brothers]

Thanks for jumping in here. I think I spoke with Tony at DCB and he mentioned you in regards to having a really good outcome on a F34 project. Tony said swap the props and I wouldn't believe the difference. But he did say that it would be almost impossible to try a set through a prop program because they don't stock that, it would have to be made. I just can't swing that money rite at the moment. The original owner said he worked with Dave and he had seen the extension plates on the bottom and said they were fine. I don't know what was done but the boat at sometime went back and forth a couple time to DCB for something fiberglass related work on the underside trying to remedy the problem???? I will get some pics and measurements of the engine and trans placement Saturday and post them. The original owner said he thought there's to much bow lift now? He told me to get some sand bags,(free) and drag them around the boat, 1st to the nose and see if it helped. Do as much low buck testing as possible before buying props. Because he (thought) when he ordered the boat he did the prop program and tried a set he (thought) that were pretty close to the 21 rake and felt no change. Like George mentioned the strakes on the bottom to help air this thing out some. I've looked at all the bottoms of the big cats and the strake goes all the way to the back. Is there no reason for that on smaller center pod cats? I'm tried of racket strapping my wife in the passenger seat so she doesn't pop out and I'm almost out of friends that will ride with me because of this. Lol. Thank you JT, I consider this an honor talking with you.

That boat pic is my reference to strakes, that all.

 

[Wright Brothers]

I cant answer the question on the boxes, I just dont know that. As far as the weight I see what you are saying. I am saying somewhat of the opposite, I tried low rake 5 blades which give the boat lift at the transom...it made the boat worse. The 4 blades do not lift the transom as much as the 5 blades and the boat ran much better. Teague found the same thing, by using a HIGH rake 5 blade that gives more bow lift. This is why I am not totally convinced it needs lift from strakes in the rear.

JRider,,, since I live close to you,, I'm just going to try all your leftovers and make something work. It's cheaper that way. Lol

 

[NicPaus]

JRider,,, since I live close to you,, I'm just going to try all your leftovers and make something work. It's cheaper that way. Lol

You Guys live close you should both meet up at the lake for a day of testing. Swap turns driving each boat and compare the bottom and differences between the 2 and swap props to test. Give you a lot of info to work with without dropping $$$$ on props that might not work out. JRider has been doing his homework save you a lot of time doing the same, hope you get it dialed in so you and your passengers can Enjoy the ride.

 

[JRider]

Thanks for jumping in here. I think I spoke with Tony at DCB and he mentioned you in regards to having a really good outcome on a F34 project. Tony said swap the props and I wouldn't believe the difference. But he did say that it would be almost impossible to try a set through a prop program because they don't stock that, it would have to be made. I just can't swing that money rite at the moment. The original owner said he worked with Dave and he had seen the extension plates on the bottom and said they were fine. I don't know what was done but the boat at sometime went back and forth a couple time to DCB for something fiberglass related work on the underside trying to remedy the problem???? I will get some pics and measurements of the engine and trans placement Saturday and post them. The original owner said he thought there's to much bow lift now? He told me to get some sand bags,(free) and drag them around the boat, 1st to the nose and see if it helped. Do as much low buck testing as possible before buying props. Because he (thought) when he ordered the boat he did the prop program and tried a set he (thought) that were pretty close to the 21 rake and felt no change. Like George mentioned the strakes on the bottom to help air this thing out some. I've looked at all the bottoms of the big cats and the strake goes all the way to the back. Is there no reason for that on smaller center pod cats? I'm tried of racket strapping my wife in the passenger seat so she doesn't pop out and I'm almost out of friends that will ride with me because of this. Lol. Thank you JT, I consider this an honor talking with you.

Someone earlier mentioned the extension plates being unsafe, I totally disagree, those are engineered damn nice and look to be very stout. I wouldnt worry in the least running them, however it would be the FIRST on my list to unbolt and try running the boat. If JT says strakes could possibly starve the props for water the "ride plates" may have somewhat of the same effect. I think the original owner is delusional about sand bags in the bow, F34s bow steer like crazy, bow bags will make that even worse...the ride plates might even make that worse as well. I wouldnt even consider this a pod boat, the 4.5" pod isnt doing shit. When Jim (previous owner) did prop testing I dont think Hering or Merc even had 20/21* 5 blades.

 

[Wright Brothers]

Someone earlier mentioned the extension plates being unsafe, I totally disagree, those are engineered damn nice and look to be very stout. I wouldnt worry in the least running them, however it would be the FIRST on my list to unbolt and try running the boat. If JT says strakes could possibly starve the props for water the "ride plates" may have somewhat of the same effect. I think the original owner is delusional about sand bags in the bow, F34s bow steer like crazy, bow bags will make that even worse...the ride plates might even make that worse as well. I wouldnt even consider this a pod boat, the 4.5" pod isnt doing shit. When Jim (previous owner) did prop testing I dont think Hering or Merc even had 20/21* 5 blades.

I agree with you about the sand bag theory. This boat has a different thought every time I make a turn. And the extension plate are very very stout. I do worry about hitting a wave and grabbing some air and those extensions touching back down 1st and stuffing the nose but when it's like that on the water I tend to back off completely. I'll look at those plate to see if I can unbolt them. I'm thinking it's going to be a nightmare when the engines are in.

 

[TEAGUE CUSTOM MARINE]

Someone earlier mentioned the extension plates being unsafe, I totally disagree, those are engineered damn nice and look to be very stout. I wouldnt worry in the least running them, however it would be the FIRST on my list to unbolt and try running the boat. If JT says strakes could possibly starve the props for water the "ride plates" may have somewhat of the same effect. I think the original owner is delusional about sand bags in the bow, F34s bow steer like crazy, bow bags will make that even worse...the ride plates might even make that worse as well. I wouldnt even consider this a pod boat, the 4.5" pod isnt doing shit. When Jim (previous owner) did prop testing I dont think Hering or Merc even had 20/21* 5 blades.

I agree I think the original owner is confused or uninformed. Feel free to throw a couple hundred pounds in the front of the cuddy cabin to confirm. More weight forward will delay the porpoise, it will make the boat stick down and run wet longer. Maybe he liked that but generally you'll get into a higher speed even harsher porpoise because of this. It will also make the low speed bow steering and leaning worse.

Speaking of which, higher rake props will help correct lower speed outside roll and lower speed bow steer. They generally won't eliminate it completely, but instead of starting to turn properly at 70 (or never) it will be 55, and the outside lean angle will be reduced in general.

As for the strakes; a lot of those true tunnel boats on tilt trailers are race boats or very close to. The hull dynamics are completely different from what you are dealing with. The tunnels are so effective and the CG so dialed in that most (all) #6 race boats turn the props out, which provides tail lift, along with those strakes all the way back. If we were to go run our race skater turning in it would blow over. For pleasure true tunnel boats it's about half in half out. They will run a higher top speed out (since you can keep the drive angle most efficient without getting nose light at speed) but are less grabby in turns when turning in, and generally easier to drive when you are driving and throttling. Also keep in mind rudder/shaft drive boats like the one you posted are a completely different setup theory.

Between 2003 (F34 era) and say 2011 CNC cleaver propellers have advanced in leaps and bounds. EVEN IF the props selected in 2003/2004 were correct and the setup was much closer, the props available now are so much better.

I would put a feeler out on offshore only. There are 20/21 deg props out there, we sell them. Even if the pitch is a few off, the handling effect will be the same. Look for Hering or Merc CNC of any generation. I don't think there are really any high rake props from before the CNC era anyways. I think nor tech 36 cats use high rake (maybe, I forget)

I honestly don't know about the "ride plates" but what they are doing is effectively eliminating the notch, which will make the x-dimension comparatively higher. I don't know if this is good or bad through a keyboard. DCB should have documents detailing where the boat was drilled, and if it's any different than the others. I would bet not. The extensions will also bring the final point of sponson leverage further back, which I don't think is what the boat needs. I don't think their effect would be too dramatic. Propellers is the first order of business.

JT

 

[TEAGUE CUSTOM MARINE]

Keep the faith. There are guys out there that love their F34's.....

 

[Wright Brothers]

Keep the faith. There are guys out there that love their F34's.....

Thank you for that info. It helps me a lot. I never had to really learn what was going on under a boat,,, I just threw some big smoke in the back and they all seemed to love it. Lol. But the 34 is different. Im in it for the long haul. I'll keep looking for props and maybe by mid summer I'll just order some new ones. Do you remember the #nos on the props you used?? I also have 1.24 ratio. I haven't confirmed that, just what I was told. I'm running 622 cu /1471 blowers 9lbs boost. I'm guessing 900 hp. I will confirm that soon as I smoked a motor 3 rides after purchase. I haven't hammered this thing down yet but we ran roughly 134mph 56/5700 rpm. The original owner said it will turn 6200??? I'm turning 16 1/8 diameter x 37 pitch x 16 degree prop. That's what BBLADES say the #nos are. And I will get some good pics of the engine bay with measurements of motor and transmissions.
Thank you!!!

 

[TEAGUE CUSTOM MARINE]

Thank you for that info. It helps me a lot. I never had to really learn what was going on under a boat,,, I just threw some big smoke in the back and they all seemed to love it. Lol. But the 34 is different. Im in it for the long haul. I'll keep looking for props and maybe by mid summer I'll just order some new ones. Do you remember the #nos on the props you used?? I also have 1.24 ratio. I haven't confirmed that, just what I was told. I'm running 622 cu /1471 blowers 9lbs boost. I'm guessing 900 hp. I will confirm that soon as I smoked a motor 3 rides after purchase. I haven't hammered this thing down yet but we ran roughly 134mph 56/5700 rpm. The original owner said it will turn 6200??? I'm turning 16 1/8 diameter x 37 pitch x 16 degree prop. That's what BBLADES say the #nos are. And I will get some good pics of the engine bay with measurements of motor and transmissions.
Thank you!!!

Your testing numbers would be 16% slip with 1.24 gears, so that's plausible. You can do a quick ratio check by seeing how far you have to turn the input shaft to make the propshaft make one complete turn. Ex: 1.24 turns on top to make one turn on bottom is a 1.24:1 ratio. Given it is pulling 37's with a 1.24, run it.

Slip should be more like 8-10%. So your high slip numbers show two things. The props are old style and inefficient but also, the diameter is too small. The "extension plates" make this issue worse, as the small diameter doesn't have enough bite already, then the propeller is effectively further out of the water. Cat props are usually 16.5", I think this boat would work well with 16.75 as well. I know that seems like a small difference in overall measurement but it is a big deal.

Also, the more diameter you have the more lifting effect the rake will have on the boat.

Problems:
1. Low rake not providing enough lift
2. Low diameter not providing enough efficiency or bite
3. Extension plates worsening both of the above.

JT

 

[Wright Brothers]

Here's some pics of the motors which seem to sit back further then JRiders F34. Measurement from transom.
1 measurement from back of back seat. JRideas boat is 7 inches closer the back seat.

 

[SkiDoc]

I owned the F-34 that Gordy out there bought. Did lots of research and one of the truths that you have to understand is that all the F-34 tunnel depths are not the same.
I bought the trailer from the F-34 that crashed and killed the owner. The tunnel depth of that one was around 2 inches shallower than my boat was. I think that its hull is the same depth of the fellow in Michigan. The boat I speak of in Pennsylvania was the one that Teague dialed in with the high rake props. I bought the props from the people who bought the salvage for the engines. They made my boat awful! I think but am not sure that Wright's boat has the deeper tunnel.
Truth number 2 is that the best handling 34's were the Bravo ones. They all are not good, but the Bravo boats were more tame. Wright's boat is extremely heavy with the tranny's and the 6 drives.
My boat liked transom lift.....
4 blade bravos awful
5 blade maximus better
increase prop shaft depth better
21 rake props rot in awful
21 rake out awful but better
18 rake props better rotation in seemed to give better overall handling
Listen to what AzGeo is telling you.
Tres Martin can add strakes and make the boat better for you if you want professional help.

These boats are very heavy.
My bottom sponsons had a definite rocker in the last 12 feet
They have relatively little tunnel compression compared to other designs and a lot of dynamic downforce from deck design

I would be scared that the static rocker plates could be dangerous in turning as the the boat does lean outward in slower speed turns. I would enclose them which would increase tunnel compression as well.

My boat was enjoyable to me but I needed to drive it. Good luck

 

[Dalton]

Your testing numbers would be 16% slip with 1.24 gears, so that's plausible. You can do a quick ratio check by seeing how far you have to turn the input shaft to make the propshaft make one complete turn. Ex: 1.24 turns on top to make one turn on bottom is a 1.24:1 ratio. Given it is pulling 37's with a 1.24, run it.

Slip should be more like 8-10%. So your high slip numbers show two things. The props are old style and inefficient but also, the diameter is too small. The "extension plates" make this issue worse, as the small diameter doesn't have enough bite already, then the propeller is effectively further out of the water. Cat props are usually 16.5", I think this boat would work well with 16.75 as well. I know that seems like a small difference in overall measurement but it is a big deal.

Also, the more diameter you have the more lifting effect the rake will have on the boat.

Problems:
1. Low rake not providing enough lift
2. Low diameter not providing enough efficiency or bite
3. Extension plates worsening both of the above.

JT

I am no expert, but calculating slip I think you're forgetting about the transmissions

 

[Wright Brothers]

I owned the F-34 that Gordy out there bought. Did lots of research and one of the truths that you have to understand is that all the F-34 tunnel depths are not the same.
I bought the trailer from the F-34 that crashed and killed the owner. The tunnel depth of that one was around 2 inches shallower than my boat was. I think that its hull is the same depth of the fellow in Michigan. The boat I speak of in Pennsylvania was the one that Teague dialed in with the high rake props. I bought the props from the people who bought the salvage for the engines. They made my boat awful! I think but am not sure that Wright's boat has the deeper tunnel.
Truth number 2 is that the best handling 34's were the Bravo ones. They all are not good, but the Bravo boats were more tame. Wright's boat is extremely heavy with the tranny's and the 6 drives.
My boat liked transom lift.....
4 blade bravos awful
5 blade maximus better
increase prop shaft depth better
21 rake props rot in awful
21 rake out awful but better
18 rake props better rotation in seemed to give better overall handling
Listen to what AzGeo is telling you.
Tres Martin can add strakes and make the boat better for you if you want professional help.

These boats are very heavy.
My bottom sponsons had a definite rocker in the last 12 feet
They have relatively little tunnel compression compared to other designs and a lot of dynamic downforce from deck design

I would be scared that the static rocker plates could be dangerous in turning as the the boat does lean outward in slower speed turns. I would enclose them which would increase tunnel compression as well.

My boat was enjoyable to me but I needed to drive it. Good luck

This is some different pics also. I think this tunnel is deeper than JRIDERS after seeing his engine placement.
The original owner said DCB did some work under the tunnel. Looks like work on the step.

 

[AzGeo]

I too have measured a number of the boats in question and they are not all the same .

Companies 'seeking excellence', always make changes and improvements .

With the amount of gross weight behind the CG, and that CG being very close to the first strake step, I suggested 'strakes' to lift that 2200/2500 lbs . (plus the leverage of props so far back)

Having 'stepped riding surfaces', I see no reason that 'the correctly sized (width) and placed (up or down the deadrise) strakes' would ever lift more that the deeper steps in front of them .

This is certainly not a 'pissing contest' on my part, just trying to offer a little insight as to what I have learned, and how it has worked out . I'm retired, I'm not looking for any more work . In the past 12+ years I have worked on or consulted on a few of these 'strake additions' (as more questions came around), and one of my friends has them on his 33', in Havasu if anyone would like to see them .

This started with a friend of mine's 33' Daytona . BBs, 14-71's, Bams, #6's . (white, yellow, purple) On Havasu, 81 MPH was "a 6' nose bounce', with drives IN, and uncontrollable above that number .

His 33' also had a problem where the 'steps' were all IN LINE, which also created some other 'control problems' .

Added strakes to the last section of sponsons, and immediately went to 'mid 130's', with the same props .

He later added 'more tunnel reduction', by filling in the 'corners' (fillets) of the tunnels, and filling the 'step vents' .

He already had a 'wide tunnel tab', which did nothing in the past, but I suggested that he add 'side curtains' to the tunnels (outer sides) . These would have extended the tunnel surface, and the 'side curtains' would keep the AIR off the props . (he did not do this, but did remove the tab)

I am sure there are a number of methods to correcting this kind of control problem, and I feel that the 'strakes' are expensive and difficult to do, but will allow the use of 'different props', for different conditions .

I would never say that the 'special props' are not 'one method', and they know it works for them . If you would like more info about the strakes, PM me .

Certainly, if you could 'borrow' a pair of special props, for CONTROLLED TESTING, DO IT !

Good Luck, test safely .........

 

[JRider]

This is some different pics also. I think this tunnel is deeper than JRIDERS after seeing his engine placement.
The original owner said DCB did some work under the tunnel. Looks like work on the step.

Kieth, are your strakes all in line with each other? It looks like the rearmost are outboard of the forward strakes.

My boat does have the shallower tunnels as Skidoc says. Really we are dealing with somewhat different boats here, Skidocs had SCX drives no transmissions with deep tunnels no pod (not sure on his motor placement), Wrightbrothers has deep tunnels w center pod #6s with turbo 400s and somewhat aft motor placement, and my boat with shallow tunnels with pod, driveline #6s and motor placement 7" farther forward than Wrightbrothers.

My boat looks to be almost identical to the one that rolled in Pennsylvania which is the same boat that teague setup. My boat seems to be pretty damn good, still does not like calm water as in the video below. 1 to 2' chop it loves. I hear horror stories of 3 to 4' hops, mine just doesnt seem to do that.

At the 3 minute mark I started putting it down and I liked that attitude of the boat, this was the day I really got the seat time and learned the boat. After this trip I straight edged the bottom to the drives and tabs then marked the indicators for neautral. It helped a lot the next time out.

Start at the 3 minute mark, straight up on the center gauge is 120, somewhere that day I made it to 127 on the recall.
[video=youtube;cqzDOeld5x8]https://www.youtube.com/watch?v=cqzDOeld5x8&t=360s[/video]

Go to the half way point and I cruize at 100 and maybe hit 120 after the 10min mark.
[video=youtube;Mwl1ZXY9vq8]https://www.youtube.com/watch?v=Mwl1ZXY9vq8[/video]

 

[Oliverdaplace]

I have the 04 f34 with N/a big blocks and xr drives, bravo 1 30p 4 blade props, only had it out once but on glassy water I started to get a slight hop around 90-95, nothing bad at all