Took the new wooden drifter sled out for the second time last Friday, this time on the Sacramento River near Chico.  We did some video-ing and I thought some of you might want to view the action.  It handled fairly well, and I was happy it would cruise at 47 mph. I took the motor and pump out of a Yamaha Waverunner 760, then framed the same size hole in the bottom of the boat. It has seven layers of glass on the bottom so I'm not concerned about it banging into a wake. Yet.

http://www.youtube.com/watch?v=UkQLEVY5tyY

 

Working on my oars now, so don't know how well it will row with what would be the equivalent of a heavily loaded boat.  I see the light green stripe on the bottom just above the chine is completely exposed when the boat is going straight which means it is drafting about three inches when on plane.

 

 

 

 

 

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that boat hauls ace and handles like a dream.  what more can you ask for?  having the driver in the bow does a great job keeping the bow down on holeshot.  looks great. 

Thanks for the nice words Justin -- I'm looking forward to some future fun, and then watching my grandkids follow in the fun.  Yes, it does "haul Ace" - what a surprise bonus that was.
Don:  The boat is fantastic!  I'm glad you had the ability and gall to try something so different.  How many horse power does the jet ski motor develop?  I'll bet others are already casting an evil eye at their kid's jet ski.

Hi Larry -- yeh, its different alright..... but not really.  Its just an inboard powered wooden boat.  My want to incorporate a jetski motor/pump into another hull - has been festering within my ego for several years.  Then I finally put together my thoughts and came up with this idea that satisfied my other want to build a wooden boat.

I asked  a couple Yamaha dealers about what HP the 760 might deliver, but without a confident answer.  An answer I wanted to beleive was between 80 and 105 HP.  Told my friend Dan who did most of the driving in the video - that my grandkids will have a blast with this boat.  Hope it stays in the family.

i personally despise jet skis.  i grew up on the long island sound w/ an ancient flatback grumman canoe and a 3 hp johnson.  they were like mosquitos (that went really fast while we were going really slow).  anytime one can be dismantled and built into something like dons jet sled it is a good day for "real boat" lovers everywhere. 
Awesome!
Thanks Josh -- nine months of just complete pleasure doing the build.  THEN - it turns out that it floats, and floats level - and the surprising bonus that it S---s and Gets!!

Outstanding.

 

It looks like it tracks great.  Did you ever consider a jet outboard before you started the project?

 

I need to finish my current boat so I can build one too.   47 MPH, be careful with that thing in low water.

 

L

 

 

Hi L -- I didn't consider an outboard in the beginning since the jetski motor/pump transplant to another hull was pretty much foremost in my mind.  But... when I built the enclosure "boxes" around the motor and pump,  It was like putting two coffee tables inside this little boat, and I hadn't realized they were so large.  So right away I was wishing I had used an outboard jet, but I have an idea this would really make it aft heavy in the water for an equivalent powered engine. One saving grace is that there is about 14" of walkable deck alongside these boxes, also from this pic you can see that I put a bottom in the aft compartment over the pump space and this will be a nice storage place for lifejackets, camping stuff,  large King Salmon, and oh yeah Beer......

 

 

Since the impeller in an outboard jet is 90 degrees from the intake it makes sense it would waste so much power.  With the drag from the deflector directing the water upward and the forward pressure generated in the pump I can see the 30 percent loss.   I wonder how much better an inline turbine pump is?

 

I have looked around and there are many turbine in-line pumps available but they are all monsters.  I have not found any 50 - 100 HP versions most are for engines above 250.  Is this the reason you salvaged one from a wave runner?

 

What size engine is in your system.  If it ran 47 MPH it must be in the 100 -125 HP range.

 

How did you seal it to the bottom?  Did you cut out a section of the wave runner and weld the two segments together. 

 

It's a great project and your outcome shows you have broken some ground here.

 

 

I've often wondered why the 30% loss with an outboard, the 90 degree gearing was my guess too. 

The 1998 Yamaha waverunner 760 that I used - I asked around and a number I wanted to beleive was 105 HP and yes for this speed I'll bet that isn't far off.  I don't have the mechanical ability to put a pump and motor together - the size selection and alignment and adapting it to the wood and so forth.  I just bought this jetski pretty much on the basis that I heard from a very knowledgeable boating friend that Yamaha was a rock solid machine and this fella had made several conversions with the jetski engines into aluminum hulls. 

When I got it home I then tackled how I was going to join the machinery up to the wooden boat.  For awhile I wondered if I had blown the $1400 and would have to abandon the whole idea, didn't have the slightest idea of how to proceed.  After much head scratching (which went on throughout the whole project) I ended up cutting the rear portion of the jetski hull out which included the integrally cast fiberglass pump, together with the mounting bolts for the engine.  There was no connection between the engine and the pump except for the loose coupling rubber or neoprene washer so it was easy to just unscrew then re-screw later with the original perfect alignment.  I made two hulls for the bottom of the boat, the first was the typical flat bottom drift boat hull which butted up to the edge of the chunk of fiberglass hull, and the second a V-hull which matched up to the intake screen and the bottom of the pump.  It ended up creating about a 7 or 8 degree deadrise (about 3") and when extended to the front of the bow it created a pretty good skid prevention.  Also I bolted a 2x6 to the back of the jetski rear step and attached this solidly to the 3/4" plywood transom.  A picture is worth a thousand words, here is a couple thousand.

I roughed up the fiberglass real good, even drilled some tiny holes - the epoxy sticks real well to the wood and fiberglass both. I used a couple hundred feet of 4" biased 8oz fiberglass tape and just taped about all the joints I could find to solidify the all the connections wood to wood, and fiberglass to wood.  I am busy building the oars now, but one of these days I want to create a build picture story so I can share with a link.  Thanks for the kind words -- Don in Paradise, CA
That really makes me smile. What a great job.

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