Aussie Seacraft 6cyl mid mount

[Bluejinx202]

Hi all. I have been putting together and now trying to sort out this little bond wood boat for a few years now.
It was built in 87, it’s a Seacraft M1. It has a Holden straight six and is direct drive. It’s a bit of a handful to drive at the moment as it’s fairly flighty but has topped out at 67mph

 

[Taboma]

Very cool boat and thanks for sharing the build pics !! Appears those boats had quite a history in Australia, ski racing and other racing venues. Checked out a couple of Youtube vids and at speed, they all seemed to exhibit a bit of a hop and loose when pushed. Best bet I'd imagine and perhaps you've already done so, would be to reach out to any "Survivors" (), perhaps they've got a few secrets up their sleeves. If you're seeing 67mph, then it seems you're now striving for that last couple of mph, which can get very dicey and expensive. There's always that chance you're little Seacraft is trying to tell you something

As a kid in the 50s-60s I recall the adventures of my dad and his racing buddy hopping up older Chris Crafts for water ski racing. Overall they did quite well, but invariably found that a boat designed to run in the mid-40 MPH range, started exhibiting strange behaviors when pushed by big V-8s well above that threshold. I remember going on test rides with my dad as he was trying to figure out why a beautiful Hemi- powered 21' Chris Craft Cobra would suddenly roll over when exiting a corner. But try as he might, it wouldn't, until race day that is
You've done an amazing job and that's one pretty boat !! Enjoy
Oh, if you get the chance, I'm curious, what are the two little holes in the bottom just fore of the keel ??

 

[coolchange]

Wow! Thanks for sharing. Have you thought about some strakes to take some " curve" out if the bottom?

 

[Bluejinx202]

Very cool boat and thanks for sharing the build pics !! Appears those boats had quite a history in Australia, ski racing and other racing venues. Checked out a couple of Youtube vids and at speed, they all seemed to exhibit a bit of a hop and loose when pushed. Best bet I'd imagine and perhaps you've already done so, would be to reach out to any "Survivors" (), perhaps they've got a few secrets up their sleeves. If you're seeing 67mph, then it seems you're now striving for that last couple of mph, which can get very dicey and expensive. There's always that chance you're little Seacraft is trying to tell you something

As a kid in the 50s-60s I recall the adventures of my dad and his racing buddy hopping up older Chris Crafts for water ski racing. Overall they did quite well, but invariably found that a boat designed to run in the mid-40 MPH range, started exhibiting strange behaviors when pushed by big V-8s well above that threshold. I remember going on test rides with my dad as he was trying to figure out why a beautiful Hemi- powered 21' Chris Craft Cobra would suddenly roll over when exiting a corner. But try as he might, it wouldn't, until race day that is
You've done an amazing job and that's one pretty boat !! Enjoy
Oh, if you get the chance, I'm curious, what are the two little holes in the bottom just fore of the keel ??

Think you are looking at the front bung drains

 

[Taboma]

Think you are looking at the front bung drains

Thanks, yes, I was thinking they were drain holes, but the location seemed odd --- or potentially filling instead of draining.
I can only guess that the way the boat sits, they drain instead of fill.
Good luck with this project, certainly a cool boat you've done an amazing job on. !!

 

[Bluejinx202]

Time for an update....Holden 6cyl out, Nissan rb25 turbo in. This new power plant seems alot stronger, I'm not sure how it will go to get going being a turbo setup, it should have the grunt when it rolls into boost though. Custom thrust unit was a bit of work but really happy with the fit out so far

 

[78DiMarco]

Time for an update....Holden 6cyl out, Nissan rb25 turbo in. This new power plant seems alot stronger, I'm not sure how it will go to get going being a turbo setup, it should have the grunt when it rolls into boost though. Custom thrust unit was a bit of work but really happy with the fit out so far

Cool boat and keep us updated with your project! Looks like fun Especially with boost!

 

[Bluejinx202]

Hi guys, Nissan RB25 is in and working. Awesome setup now, very happy with the result. Making similar HP to my n/a engine but without the negatives of a pretty cranky race engine. Performs very similar out of the hole and reaches same top speed as a standard engine on low (7psi) the engine is built to handle 20psi but I doubt I'll turn it up anywhere near that.

I still haven't got the porpoise out of it yet, I think now I have the new engine done props will need to played with? Does the round ear vs cleaver type props lift and drop the stern like I've read they do the outboards?

Should I post this in the v drive section for advice?