1977 Hydrodyne Tournament Skier 18 OB Rebuild

I've been running SST HighFive (5 blade) props for the last 10 to 15 years and really like them for double-booted pull out for slalom. They are a bit pricy (~$450 new) and would suggest that you experiment with aluminim three blades to get a feel for what you need. The 75 HD I/O 351 CID 233 HP 2 Barrel came with a 21p three blade SST and I tried a 17p HighFive but the RPMs were a little high. Brought a 21p Highfive and the 75 gave up a bit of torque but worked fairly well. I have that same prop is on the 85 I/O 350 CID 260 HP 4 barrel and has great holeshot and top end speed. A 19 pitch would probably be a good choice for you in a highfive but see what the aluminum three blade does with the current motor. The throttle you are dealing with is a Mercrury and not a lot of flexibility. For the I/Os, I hav always run moris or telaflex throttles and they hide the cables up under the gunnel nicely. You can change out to the aforementioned but you will need to understand the travel or throw of the throttle and see if it works for you.

 

This is what I recommend for you:


https://www.partsvu.com/yamaha-flus...Fp8yIGity3ZSlo_IlQAkjmMT3ba3R1jxoCsYkQAvD_BwE

You will also need the Yamaha dash mounted ignition switch if it does not come with it. You will also need to splice into the trim wiring. It is a MUCH better set up.

jim

 

Well folks, it's so close I can smell the exhaust!

Jim and Kevinb thanks for the tips. The prop matter will just be food for thought till we actually run it and start to fiddle with performance. As far as the controls go, Dad did some trimming of the side panel and set the controls lower on the side, allowing the cables to pass directly under the gunnel without any serious contortion. I think it came together pretty well. Since the last post the Dyne has seen almost all of the remaining details finished. Here are the pictures:

Dad put in a fair amount of elbow grease and the factory pylon came out looking great. He also did some minor modification to make the pylon removable with pins for storage.


Motor is finally off the stand and ready to hang.


The primary step is complete in converting it from a row boat to a ski boat.


Adding the rub rail. This step was a lot more of a bear than we anticipated. Mounting the base was tricky, and putting in the insert took us about 5 times longer than we would have thought. By the end we had our technique down. I guess the next Hydrodyne rebuild will go much quicker


Finishing the rub rail was pretty rewarding though. Cosmetically it was really starting to come together.


Carpet is in, looks comfy. The angle of the controls looks kind of funky from here, but it's an illusion. Sitting in the boat it's comfortable and the placement is good. Steering, gauge panel and gauges, glove compartment, stereo and accessory panel are all complete.


Seats are in. The driver's bucket is adjustable front to back. The passenger bucket is on a locking swivel for spotting/cruising choices. Rear bench is in with rear speakers. Bench seat folds down and forward to access under seat, and the entire seat has two release clips underneath to slide the seat forward completely to access the battery, oil tank, bilge area, etc.


And of course, the stripes!

The boat is currently water ready. Hopefully we'll be taking it out in the next couple of weeks. Stay tuned!

 

Nicely done!

 

X2 to Greg's post. Time to put that boat to work. Not an outboard guy and don't know too much about the Mercury Force. Hope it meets your expctations

 

Thanks guys. @kevinb it's a Mariner rather than a Force. Force motors were highly contested depending on the age range, but the majority opinion seems to be that Force were no good. My personal experience with Force was with the first boat in our family that I remember and the one I learned to ski behind, a 1985 Bayliner with an 85hp Force outboard. I remember spending a fair amount of time watching Dad fume at the motor with the cover off, if it's any indication of the Force line. What we've got here is a 175 Mariner Magnum EFI, which would be identical inside to a Mercury XRI, just gray instead of black. Between personal experience with them and what I've read online from others, this era of Mercuries/Mariners were some of the best motors you could buy regarding power and reliability. Barring any unforeseen issues this motor may have which we couldn't find while bench testing, this should be an excellent fit for the boat and pull anything we would care to pull with it.

 

Opps.... Guess I need to read the stickers on the engine cowl instead of looking at the color of the engine.

 

If the 19p prop pulls hard enough for you, it will be fine. A 16 or a 17 will pull harder. I use a 17 with the cup removed. Over revving is not a concern with that motor. It has a rev limiter. Mine a will hit the rev limiter with no skier. I also have a torque shift for playing. It is variable pitch and self regulating. I think it starts out at 14p and increases as the engine nears the red line.


Jim

 

Well, we officially had the first shakedown run this last Saturday. Overall I'm going to say it was a success. 1) It floated! That's a big performance booster for a boat in my opinion. 2) Got tons of compliments right at the landing. 3) Started and ran great. Dad was pretty happy with the acceleration. Both of us drove it, and it was too busy on the lake to get a true gauge of the performance or top end. It handled even better than I imagined. Maybe I was biased but it seemed to handle much better than our team's 20 footer, and I was very surprised at how it handled chop and rollers for a small boat. After about 15 minutes of tooling around we started to notice an issue with the temperature gauge. Checking in the back showed no water coming out. We shut it down and got a tow in from our backup boat. My first thought was an old, rotted impeller. Dad pulled the impeller and it looked brand new and was still supple. Poked around to clear the spitter then fired it up in the driveway a couple times and everything seemed to act as it should. I believe it was a wiring issue with the temp gauge, coupled with a clogged spitter, suggesting a cooling issue. It seems now that there's no true issue with the cooling. There were a couple other issues with gauges that I believe Dad has fixed now. Hopefully run #2 will go off without a hitch!




It's a family project! Dad has lovingly deemed it 'The Orphan'.

Hopefully next time he'll be pulling skiers!

 

Nice looking rig and well thought out. the bubble top (instrument cluster) is an iconic design. Heading north on Wednesday without the 85 I/O 20 (too many other options up north and will not deal with a trailer following me in traffic). Need to put some more yellow tone in that gold bow stripe next time around.