8' Hydro Play Boat

[bsmith]

I have acquired an early 70's 8' long all wood (no cloth cowling) little hydroplane. It is about 50" wide at the sponsons and the transom is 16" high. It looks similar to modern A stock hydros except the combings do not come near as high. Consequently, you have to be very careful not to swamp the boat. A 60's era 15 hp Johnson came with it in fishing form which means the lower unit goes way too deep, but you do have neutral, forward, and reverse. With a stock prop the little boat does a none too thrilling 22 mph.

The boat is too dated and heavy to justify putting a proper racing engine on it for someone who races A hydros. It is confined to use on a private water ski lake as a kind of play boat that is both slow and still has to be carefully used. I can modify the combing to be higher, but I don't know what to do about the engine situation.

I don't have to worry about racing or any lake regulations so engine options are wide open. I would like something that you could pull start easily (electric start ok) and at least have a neutral so you could cruise around and start and stop without having to shut off the engine. I would also like to have enough power to push an adult to 40+ mph.

Maybe the old Johnson 15 has enough power to go 40 with the little boat and just a higher pitch prop is all that is needed. But with the lower unit so deep and dragging so much, I don't know how far you can go with just changing the prop. I suppose also that the engine could be perched way up by extending the transom in some strong way, but I am not sure how far you can go with that approach and still be safe plus you have to make sure the water pickup point of the stock lower unit stays in the water.

I also have an early 70's Merc 20 fishing motor that is super heavy, but much more powerful than the old Johnson 15. Of course, the merc has a long lower unit as well. Since I got the boat free and it is quite a novelty and has good fun potential, I am willing to spend some money on it and maybe go with a completely new engine. But again, I want something in a mild state of tune that starts easily, allows some idling, has a neutral and maybe reverse, and yet is still light enough and powerful enough to work well on the little boat and achieve 40+ mph. Any ideas?
Bill

[jsilvestri]

Hi Bill. Its sounds like you have an old 60-J hydro. This would be a boat built for the junior or kids class and at that time a little Mercury racing engine was the motor that was run on the boats. I'd suggest you find yourself an older used A(9'),B(9-'6"),20(10'),C(10'-6") boat for what you are wanting to do. I'm sure there are guys and gals on this site that have what you are looking for in the buy and sell section. Or, maybe someone that has what you are looking for will see this thread and chime in. I wouldn't suggest putting a bigger motor on the boat you have. Good luck.

[bsmith]

Joe, the owner prior to me said the first owner mentioned that a 9.9hp mercury racing engine with a "quicksilver foot" was what the boat was intended for and the long shaft fishing motor was just an experiment. I agree that any of the boats you mentioned would make a better play boat than this old and tiny 8' hydro. But wouldn't you still run into the same engine problem if you want an engine with a short lower unit and speed prop that can idle and shift gears (neutral and reverse) like a fishing engine? Does such an engine exist? If not, it explains why I never see B and C class hydros and runabouts ever used as play boats in the same way that PWC's are used. Outboard racing would be helped greatly in popularity if people had an easier way to play with those boats in a non-racing environment. Bill

[jsilvestri]

Bill, I believe the only race engine that utilized a stock fishing lower unit was the 36 class, which has not been around for some time. All other engines use a racing lower unit.

You would be able to use a fishing lower unit on a racing hydro with no problem because you want to run the boat for fun. I certainly do not blame you for using a fishing motor as is. You would be able to put a big enough engine on a bigger boat to achieve the speed and flexability you are looking for, just not on the little boat you have.

[bsmith]

Joe, I have been under the impression that even the boat sizes you mentioned, A(9'),B(9-'6"),20(10'),C(10'-6"), would not work well with stock motors and their long lower units. But I guess what you are saying is that while the engines would be slowed quite a bit from their full potential, you could still enjoy the niceties of idling in neutral, going in reverse, and still have a reasonable top speed. But on a tiny 8' hydro, you just can't safely use a big enough stock engine to overcome the drag of a deep lower unit and still obtain a decent top speed. Oh well, I may make one try at perching up the fishing 15hp motor I have and putting a larger pitch prop on. Bill

[jsilvestri]

I wish you a lot of luck. Hopefully, it will work out for you and you can have some fun with the little hydro. Post a picture of the hydro if you get a chance.