Custom/Hybrid Complete build. Custom flat water carver ski.

[Bulletbro]

hey, started this a while ago and found some time to get a bit more done on it over the holidays.
Plan is to build a ski for long rides on a flat lake I live near.
My Superjets are ok but they porpoise a lot and slide around on long carving turns at full throttle, especially when low on fuel and nose lightens up.

Started with a WR 3 and cut the floor to include pump mount and engine mounts.
Chose this because engine is further forward than SJ hull.
It’s also longer from pump to bow so will have better top speed as sit down skis do.

 

[Bulletbro]

Doing a ply/fibreglass sandwich construction.
Epoxy glass, woven matt and woven edge tape.
epoxy/aerosil/talc to make filler/roving.

Building a sharp edge (reverse chine rail) sure will be interesting to see how it corners.
Practically a flat dead rise with reverse chine will be edgy but the tray will be wider so your body weight can be positioned right over the chine, almost inside it when banked in a corner. Goal is to get it to hang on better during full throttle carving turns.







Layer of bi-ax cloth.


Structure/shape done and glassed.


Sand and epoxy primer/filler

 

[Bulletbro]

Next will be Flo coat the bottom. I’ll post when it’s done.

Engine is starting as a 61x 701 with twin carbs (38’s)
Using a blaster pipe for starters, I want to get it on the water and see if it handles ok before I pour a heap of $ into hot parts.
If this thing turns out to be a widow maker, then I don’t want to be embarrassed and broke. Just embarrassed is ok...

 

[CD155MX]

Subscribed!

 

[jetx]

cool build

 

[Just4Fun]

Great start! so are you planning to drop the sj top deck on this?

 

[Lumberjack]

Woahhh wild build. Subd

 

[Bulletbro]

Great start! so are you planning to drop the sj top deck on this?

I was thinking that a SJ top would be quicker but I’m getting the feeling I might just custom the top too.
I just don’t want it to look “homemade” if you know what I mean.
I’m planning on using a SJ pole/steering for starters and going bling if it goes and looks good.

I think I’ll start a custom top and see how it’s looking, if not good enough I’ll put a SJ top deck on there. Gotta give it a go.

This has some straighter lines on it. I’ll take some inspiration from this.

 

[loictahiti]

Awesome job
Subscribed right now

 

[Bulletbro]

Sure hope I can keep you guys entertained..
Spent today sanding and filling the primer on the hull and fixing any imperfections before flo coat tomorrow morning.
Bit of time on the lathe and mill in the machine shop machining the carby throttle shafts to suit the r&d 61x twincarb reed plates as the carby centres were out and throttle shafts were hitting.

Had to extend thread and flats 12mm, I’ll cut off the excess when I mount it up.

 

[Sanoman]

Subscribed!

 

[smoofers]

Definitely subscribed. This is awesome. Great work.

 

[iangdesign]

Sub'd

 

[Bulletbro]

Flo coated the hull base today.
Used poly Flo coat natural (clear) with black pigment in it. Couldn’t buy it in black? Could get white though?
I’ve never used this product before but the finish is not bad, I think with a bit of practice and better prep you could get a near mirror finish, at least as good as your average car paint job.

From what I’ve read, it’s basically a poly gel coat with waxes added to “self level” and give a gloss finish (when you don’t have a mould). Was pretty easy, applied with spray gun.



The rest of the hull was done in epoxy resin and I read about a hundred different opinions on the bonding of the 2 types of resin.

Finally there was a YouTube clip where he basically did bond failure tests on this debated topic.
He proved that (in his hands) the bond of polyester resins to Epoxy resins is sound, at least as good as polyester to polyester.. so I went with that.
Apparently it’s easier to get a good finish with polyesters than epoxies for the novice.

Tip.... best paint/resin mixing head for your drill ever.. cable tie on a 6mm diameter rod.


Nice thick coat.



While colour coat drying....

Mounted the carbys up.
Throttle shaft had to be shortened 12mm to allow clearance, shortened spacer and throttle return spring.



This R&D twin carb manifold for the 61x case must have been for 44mm carbs. Had to remove old threaded studs and re-drill/tap and replace studs on the manifold to suit the 38’s I had.



Next will be put the pump in and prep to drop the engine in. I need it all in place to fab up the top deck and clear that big blaster pipe..

 

[rowsto]

Damn now that's different, nice work!

 

[CD155MX]

Tip.... best paint/resin mixing head for your drill ever.. cable tie on a 6mm diameter rod.

haha brilliant!

 

[Jhucke]

subbed, this is sweet.

 

[Bulletbro]

The Flo coat is hardening up. Leaving it in the sun for the day.



I know this is vintage pump gear but it should run ok.
New pump housing with delrin liner.

Skat trak 14-17 Stainless impeller that I have on the shelf for starters, if it goes ok I’ll get a tall impeller for top end speed.





I’m going to custom a ride plate as the WR3 ride plate won’t do. I’ve got this idea to do a chop/extend the stock plate and make it like the worx plate on the SJ. For another day.

 

[Yami-Rider]

Are you going to build a ski using that bottom deck or is that your plug for a mold?

Not sure how well some plywood and wet layed glass is going to hold up under actural freestyle conditions.

Interesting project for sure.

 

[Bulletbro]

Are you going to build a ski using that bottom deck or is that your plug for a mold?

Not sure how well some plywood and wet layed glass is going to hold up under actural freestyle conditions.

Interesting project for sure.

Hi, this is for the actual hull at this stage. Could be used for a plug but I’m not sure how it’s going to handle on the water so i’m going to run it first.

A “sandwich” construction (fibreglass either side of ply) is actually pretty strong, a well known way to build boats when you don’t have a mould.

This is not really for “freestyle” riding that you “backflip powerhouse motor” riders are into, I agree with you that it would most likely fail under those conditions.

It’s basically designed for flat water carving wide turns at full throttle. I’ll reinforce this hull internally for that, if I get air on this, I’ve missed the brief.