jet boat project with pics

[Scubaproh20]

I am building a jet boat out of my 14' boat and am using a yamaha jet pump, still gotta decide what motor to use but this i know I needa complete motor pipes carbs mounting plate etc. I want 100hp minimum so far im looking at sea doo 787 and yamaha 800. my current problem is I cannot figure out if the pto couplings are threaded tapered or both and which ones will share a common pto coupling to my 1998 yamaha gp800 pump.

 

[Scubaproh20]

Re: jet boat project with pics

does anybody know if the crankshafts on yamaha and seadoo are the same thread/taper

 

[Ernest T]

Re: jet boat project with pics

SeaDoo and Yamaha drive shafts are totally different beasts in every dimension. If you are using a Yamaha pump, stick with a Yamaha engine and make your life much easier. Plus the pump is set up for a particular RPM to operate at peak efficiency. If you try to run a pump higher than its rated RPM range it may tear itself apart......too little RPM and it never runs efficiently. Bottom line is that the engine and pump are matched sets, you can't mix and match and expect it to work.

 

[86 century]

Re: jet boat project with pics

+1
My seadoo runs at about 7000
Dont think the yamadog is that high

Best coarse of action would be to find a crashed ski so you have it all.
All the small part can get exspensive real quick.

How heavy do you think your rig will be. If you are moving with 10hp now 100hp may be alittle much.
Good luck.

 

[Ernest T]

Re: jet boat project with pics

Yea, your best bet is finding a used ski with a smashed hull, but intact engine and electronics. You are going to need the whole package: engine, pump, wiring, ECU, guages, etc.

 

[Scubaproh20]

Re: jet boat project with pics

i actually have a 40hp evinrude electric cshift, im going to a tigershark daytona 1000, weight will be a minimal increase, but will not be hanging off the transom, the yamaha pump is a 144 mm dia with a 15/20 pitch impeller the tigershark is a 146mm with a 12/23 impeller , the yamaha should have a far cleaner install where the tigershark pump will be fiberglass on aluminum both are close in hp 115/120 by comparison the yama runs at 7350 cruising the tigershark i have no idea , but i need to factor the boat into the equasion. it is 350lbs as it sits no motor. 550 with that old evinrude top is about 50lbs or so I have to wait and see but the tigershark daytona 1000 im picking up might have electric trim.

 

[Scubaproh20]

Re: jet boat project with pics

btw, it goes 22mph loaded 3 ppl and gear the tag says 1450lb capacity with 40hp the cabin acts like a giant ebrake but is extremely comfortable in the heat rain or sleet and is very strong ( can sit on it)

+1
My seadoo runs at about 7000
Dont think the yamadog is that high

Best coarse of action would be to find a crashed ski so you have it all.
All the small part can get exspensive real quick.

How heavy do you think your rig will be. If you are moving with 10hp now 100hp may be alittle much.
Good luck.

 

[86 century]

Re: jet boat project with pics

I started but never finnished a similar project.

I found out real quik that the eng and pump need to match quit well.
The tiger shark would be a good choic if it has a wide range of impellers avalible.

 

[Scubaproh20]

Re: jet boat project with pics

On wednesday I picked up a TS 1000 now I have to build a transom adapter box thing, and find a teleflex cable for the yamaha gp 800 pump / my current steering. im building the transom box out of 3/32 or 1/8 aluminum not sure but im using 2'' angle to support it OH good news the yamaha couplers do indeed fit tigershark engines such as the rumor said. proof in in the pudding. btw I have alot of tigershark pump parts for sale mint 651 308 0584

 

[Scubaproh20]

Re: jet boat project with pics

Today I made the hole for the pass through for the pump, It will be a square plate when I cut out the piece out and will bolt to a transom adapter im in the process of making to match the output angle of the pump. I used a dremel tool and am very impressed how accurate and perfectly round it turned out for a 10$ adapter and 3$ bit!

 

[silly34]

Re: jet boat project with pics

cool!

 

[Scubaproh20]

Re: jet boat project with pics

Got the pump mounted and the engine mocked up, I found a teleflex jet boat steering setup that should work with it too . Btw it should be considered an understatement that it was easy to make the pump adapter thing, I removed the keel about 20'' from the pump inlet. and sealed it all up I used 1/8'' plate for the fabbed up adapter plate

 

[Scubaproh20]

Re: jet boat project with pics

oh i moved to tinboats.net and the boat is done does over 40mph and gets there very fast.

 

[PSG-1]

Re: jet boat project with pics

Hey, scubapro! I didn't see this thread before, or I would have responded to it sooner. Excellent work on your jetboat.


Contrary to popular belief, you CAN mix and match pumps and engines, as long as you have a lathe and some basic machining skills....simply modify the pump shaft for one half of a spartan jaw coupler, by cutting threads on the shaft and in the coupler, then modify the other half of the coupler for the threads on the PTO of the engine. And then you match RPM by stepping up or down on the impeller pitch, sometimes it will require sending the prop out and having it re-pitched to a custom pitch if that particular pitch is not available from a factory.

Your boat project proves that it CAN be done, and anybody that thinks that was just a lucky fluke, my boat originally used a TS1000 engine and a Yamaha XL1200 pump, before I went to the 4 stroke.