grant118

My Feedback: (26)

has anyone ever tried to use a 100 cc twin engine in a boat? I was think of building a 1/5 scale unlimited scale hydroplane and wanted to use an engine this size.

Justaddwata

My Feedback: (3)

I cannot say I have seen more than one or two large aircraft adaptations into a boat and no not of how successful they were.

What you might want to consider is more the power and RPM of the motor than the size. Aircraft motors are not always great transplants into marine applications. That said I have seen the 74cc Zenoah twin marinized a decade or so ago by Ballantine Marine as an option for his production boats though not very popular and not very potent. He also marinized the G62 zenoah single which has gobs of torque but no RPM. I have 3 of these myself. The G62 swings a 9515/3 (95mm) prop but only revs to around 11000 rpm - may well be reving lower under load. http://photos.imageevent.com/justadd...e/IMG_6209.JPG

Realistically you will likely see more HP and more RPM and considerably better results + not have to deal with cooling issues if you consider an inline marine motor like the RCMK or perhaps the single cylinder but powerful Mathe 35cc or CMB35RS motor. I would recommend researching these options a little further before reinventing the wheel with an aircraft motor.

Here is a large hydro with a Mathe 35 http://photos.imageevent.com/justadd...e/1treff10.jpg I have no info on the performance.

Here is a 4cyl aircraft motor in a boat - again unknown performance - http://photos.imageevent.com/justadd...tled17.bmp.jpg

Certainly keep us in the loop and maybe start a build thread so we can follow along!!

grant118

My Feedback: (26)

Thank you JAW. I would like to build a large scale unlimited hydro and would like to have decent power. You are most likely right though. Most of the airplane GAS engines that I have do not rev more than about 8000 rops so probably not fast enough. Maybe if I make a speed increaser gear box...??? I'l keep researching it.

Ron Olson

My Feedback: (1)

In the long run you'd just be better off by buying a marine-specific engine like a Zenoah 260. They're dirt cheap right now at around $165.00. Gizmo Motors (.com) has those and the new Tiger King for the same price. Bruce also sells modded engines really cheap also. It'll also the lack of hassle in mounting up the engines and associated parts.

Hydro Junkie

I'm going to have to agree with Ron and JAW, use a marine engine. In this, I do speak from experience. I built a Dumas Pay'N Pak kit back in 1982 and, since it was available, bought an HP 20 marine engine. What I didn't know is that the engine was nothing more than an aircraft engine with a water cooling jacket. Unlike the true marine engines of the day, this engine kicked out around .5 HP at a maximum of 17,000 RPM. For an airplane, these stats are great but not so for a hydroplane. A few years back, I bought another one of these kits but, this time around, I used it as templates.The finished boat ended up lighter, wider, lower and was powered by a Nova Rossi .21 marine engine. Unlike the HP powered boat, this one was able to get up on plane, even though it was running VERY rich and burning 20% nitro helicopter fuel. To make this engine run properly, it really needed some 50% fuel. The NR is rated at well over 1 HP and 35K RPM, much better suited for a performance boat

MATHO

the pic Justaddwata showed with that 4-cyl. boxer was built in Germany by Armin Winkler, the boat is a HPR190 (Giesse) but it never saw water with running engine. Reason: much to heavy!!
If you want to see big powerplants for model race boats: www.matho-powertrain.de
have a look!