Imco SC lower questions

[Dcb.blake]

I’ll be upgrading to a new lower unit due to my stock xr just not being efficient at speeds the boat is capable of. The boats a DCB F26. My question is how do I determine if a -2 shorter lower would be sufficient for me. Is there some sort of measurement to be done or is it one of those situations where you just throw the lower on and see what happens. I know you can get spacers but I’d like to get as close as possible.

 

[farmo83]

I would call Bob Teague and see what he thinks. I'm sure he's run across setting up that hull with various levels of horsepower. He'll have whatever you need on the shelf too. He covers X dimension in one of his youtube talks as well.

 

[02HoWaRd26]

Whole huge can of worms..... in all reality I’d suggest sending @Tony DCB Boats a private message. When i bought my boat it had a stock XR on it, but i had a fully built MMW drive on my other boat so i swapped them. That landed me at -1” after some playing removed the spacer to bring it to -2” the boat was real unhappy than, so back to -1 till i found a 2” spacer. I did the 2” spacer Thursday night, and the dam run was first test. Boat was wayyyyyy happier back at the 0 height, so that’s where it’ll stay.

 

[Dcb.blake]

Hmm I’d be curious to see what others are running. Are you running an extension box? What prop and speeds are you getting?

 

[02HoWaRd26]

Hmm I’d be curious to see what others are running. Are you running an extension box? What prop and speeds are you getting?

Standard setup, no box, 525efi, Max5 26p this weekend we didn’t push it, VesselView showed top speed at 73 this weekend, but lots of gas and gear. Been 85.4 this year but was light everything. My boat is vacuum bagged kevlar but I’m also midcuddy open bow so you’re probably a bit lighter with closed bow

 

[Dcb.blake]

Yea I’m running a bravo 4 blade 28 and with full load fuel gear people I can hit 92ish when water permits

 

[Dcb.blake]

Really been eating go try a 26p just to see what it does. B blades is having a hard time getting props so they are not doing to prop rental service currently.

 

[02HoWaRd26]

Really been eating go try a 26p just to see what it does. B blades is having a hard time getting props so they are not doing to prop rental service currently.

Where do you boat? I have a Max5 26p, Bravo 28p and a Bravo 30p that’s been worked down to a 29p.
If you boat around needles and I’m home from work I’d let you test the 26 or 29 to play.

 

[Dcb.blake]

Where do you boat? I have a Max5 26p, Bravo 28p and a Bravo 30p that’s been worked down to a 29p.
If you boat around needles and I’m home from work I’d let you test the 26 or 29 to play.

Ah I wish I lived closer Id love to give them a shot just to see what happens and see how the boat reacts. I’m from the central ca area. My dad has a 24p I may throw on just to see what happens

 

[02HoWaRd26]

Ah I wish I lived closer Id love to give them a shot just to see what happens and see how the boat reacts. I’m from the central ca area. My dad has a 24p I may throw on just to see what happens

Why do you want to go backwards with props? If you already get limiter (what rpm are you at now) and 92mph a smaller pitch prop will just be quicker acceleration but lower top speed.

 

[Dcb.blake]

Why do you want to go backwards with props? If you already get limiter (what rpm are you at now) and 92mph a smaller pitch prop will just be quicker acceleration but lower top speed.

Just kinda curious to see how much it really affects the boat. Be nice to gain a little better plane and mid range power and loose a few mph off the top. I normally cruise at 70-75 anyways. My rev is at 6k but my motor at least in my tach only shows 5k when I’m to the woods on the happy handle

 

[Mcchevy69ss]

Just kinda curious to see how much it really affects the boat. Be nice to gain a little better plane and mid range power and loose a few mph off the top. I normally cruise at 70-75 anyways. My rev is at 6k but my motor at least in my tach only shows 5k when I’m to the woods on the happy handle

With the performance numbers given, your set up is already extremely efficient. 5k rpm = 92mph / with a 28p 4 blade. That is 6% slip assuming you have 1.35 lower gears. What motor are you running? If you switch to a Max 5 you will gain a lot more low and mid range grip, but you will likely want to prop down to a 26p.