Hydroplane Engine Help

[Seanj85]

I hope I am in the right place.

I am a shop teacher in Long Island, NY and am gearing up to start a major project next year for an advanced materials processing class. The class consists of 8 upper classmen high-schoolers and each year we build a major project together. This next year we are going to build a hydroplane from clark craft, its the 11'3" ben hur. I have already got the plans, hardware, most of the materials and epoxy & fiberglass kit for it, I am just not sure what engine to run. The plans state it can hold an engine up to 60 hp and was curious if anyone knows of a good engine in that range that makes good power to weight. I think it would need to be a 15" shaft, but we might be able to alter the transom to support a 20".

The plans state: "For the non racer who would like a big hydro that will take two people with safety for a fast, safe, soft ride, Ben Hur would be ideal. This hydro is as simple as possible to build, no extensive jig is needed. 36 pictures of construction and action, full step by step building instructions, full size rib drawings, scale drawings, some tips on setting up and a complete bill of materials. Meets all APBA specs for "C," "D" and "F" and will take any motor from 25 to 60 hp."

If anyone can point me in a direction towards anything for sale I would also appreciate it. Since I cannot buy a used outboard thru the school it will come out of pocket, so I need to be budget conscious. Along with basic maintenance I can do carb rebuilds and more advanced stuff like a hone and re-ring but would like to stay away from a total overhaul project motor.

Any help would be appreciated
thank you

[Capt.Insane-o]

Yamaha made a 15 inch pro v 50, they are like unicorn farts now but a great little motor.

[XstreamVking]

yamaha also made a crapload of 40 hp motors. Same 2 cyl motor. They are cheap, use common props, fairly light, and on a hydro weight is critical. Even more critical is easy parts availability. People are trading 2strokes for 4 strokes. Should be some available. Maybe check some marina's for a donation engine.

[Seanj85]

Great info, I I see those motors w/o trim weigh 130 lbs. I would prob remove the starter if possible to shed some weight too.

[99fxst99]

Donation engine came to mind with me too. I wouldn’t sacrifice the electric starter for a project like this, you want ease of operation for your class, not chasing records ;-)

[XstreamVking]

No starter, no batt saves a lot of weight. Let them pull start it. 2 pulls and it will light off when cold. 1 pull when warm. Those engines want to run.

[Seanj85]

Do you think I would be okay running a 50? It says it can handle 2 passengers so I am thinking if I can offset the weight of the motor by running one passenger.

[rock]

Do you think you might be OK with a 70 Merc. I have a powerhead I would be willing to donate. The mid is OK but no trim and the lower is junk. Motor ran well.

Rock

[SS Minnow]

Do you think I would be okay running a 50? It says it can handle 2 passengers so I am thinking if I can offset the weight of the motor by running one passenger.

It would be OK with a 50, but it would be much better with a Merc 70. Might need to make another brace here, or a taller knee there, but it would work.
Look forward to seeing this happen.

[Seanj85]

Do you think you might be OK with a 70 Merc. I have a powerhead I would be willing to donate. The mid is OK but no trim and the lower is junk. Motor ran well.

Rock

I would definitely be interested but have a few questions. What year, weight and shaft is it? in an effort to keep things light I would want to delete trim. How hard would it be to find a lower? Keep in mind we will not be starting this until after the summer this coming school year.

Thanks!

[rock]

I will have to do more investigating but I think I may have also found a 15" mid and lower. Don't know the year off top of my head and have no clue as to weight. This powerhead belonged to my neighbor at my cabin. He ran it from the time I met him till he bought a 4 stroke. I looked at his boat one day and all but demanded he bring it to my shop. Most dangerous rig I had seen and he was very old and movement was a bit iffy at best. I re-did his deck to remove all the tripping hazards he had which made me feel better. When his lower unit went out he asked if I could do the motor switch for him and after removing motor he told me to put it in my truck. I never charged him for any of the work I did so I guess he felt it necessary to re-pay me even though I did not. The mid is a 20 and lower is shot.
Today while rooting around in my mess I think I found the correct 15" mid with a lower attached. No trim unit and I think that is why it was hidden in the depths of my shelving. It will be a few days till I can pull powerhead and see if it will fit this shorter mid. If it is all there and will work for your kids you can have it all for the price of shipping and the box.

Rock

[Seanj85]

Rock, I don't know what to say other than thank you, thank you, thank you! This was the only thing that i was unsure about in keeping this boat come to fruition. I see you have a fastenal in Pekin, their shipping from branch to branch is very good if you want to go that route. I will PM you my information, like I said it is no rush, we will not be starting til end of summer. Thank you so much!

I will do my best to document this build, what part of the forum is best for that?

[97mirage]

Rock is a great guy and helps all of us on this site. There is a section called “Boat Build-Ups and Restorations”...probably best to document things there.

[David - WI]

I'll help with the shipping cost, if this goes through.

[rock]

You are very welcome Sean. As a retired cabinet maker I get to see someone do exactly what I have wanted to do but never had the time. What I hope is this project lights a fire or two and helps this sport continue. Seems there are very few youngens getting involved anymore. I hope you are mechanical as this is no "turn key" motor. I believe everything you need is there but there might be minor wiring issues to deal with and I wouldn't trust any of the plumbing. As you know there is a lot of help on here for both construction and mechanical. It's a good day when you can clear out some space in the shop and help a bunch of kids at the same time.

Rock