sterndrive for 16 ft powerboat

[andreirochian]

the most suitable engines for the 16 ft pwrboat we are actually designing/building , seem to be 130 hp,3.0l mercruiser/volvo penta stern drive.
the weight seems to be too much/300 kg,so the next option should be a smaller inboard gasoline engine.
the smaller ones on the market seem though to be the ones mentioned above.
your opinions on this subject may help.

[Jeff]

If the weight of a traditional engine block is too much, maybe a rotary engine would fit the bill:

http://www.rotarymarine.com/

I have no experience with Rotary engines, and there may be drawbacks such as fuel consumption, ease of obtaining replacement parts in various locations, etc. but it might be an option for you to consider at least.

[David Dobbs]

Are you set on a Stern Drive?

How about a small mercury SportJet jet drive?

Impeller Horsepower: 175 (131 kW)
Weight (lbs/kg): 305 lbs/139 kg

[andreirochian]

I do not have expereience with rotary engines, but I ll do some research,
regarding the small jetdrive it seems to me the customers that we are targeting tend to be cautious to "new" stuff but I ll look also into this option

The SportJet is in large part a Mercury outboard powerhead, so it is well proven in a way. Also lots of them are used in jetboats all over so that's good for getting parts and service.

Or are you thinking of the image of a jet vs. conventional propulsion system?

[David Dobbs]

Another small engine which might be an option depending on the type of boat is Bombardier's Rotax used in SeaDoo JetSkis and Jetboats. http://www.rotax.bombardier.com/

They come in 130 and 170 hp varieties and they are light.

Jon Lauter of Rotary Power Marine Corporation here...

Regarding the questions about the rotary marine engine, here are some points to consider:

Two models available, 175c (175hp, carbureted); and 240Si (240hp, supercharged, digital MPI and DIS). The 175c weighs 315lbs, the 240Si weighs about 340lbs, INCLUDING standard fresh water cooling.

The engines are just slightly larger than a cube 2' on a side (the 175c is actually less than 24" high from sump to top most point).

The base block is the well-proven Mazda 13B, made specially for our use in marine applications. The basic engine block is exceptionally simple and durable, and runs with virtually no vibration. Most of the accessory systems are conventional in nature, and easily accessible for service. The starter, alternator, oil filter, remote oil drain, carburetor, etc. are all top mounted. The engines have a single 3" exhaust. The four spark plugs are located on the opposite side from the exhaust and are easy to get to.

We have established distribution channels in the US for product, parts, and service (Mack Boring and Parts Co in the mid-atlantic, northeast and midwest, and Southern Power and Lights, Houma LA in the Gulf region). Parts can be anywhere in the world in a matter of a few days with modern overnight services.

The rotary engine is a true four stroke engine, and offers excellent fuel economy in marine applications. First of all, the engine is very light, so a boat may weigh up to 1000 lbs less than it would with twin piston engines. Second, the rotary is designed to run at higher speeds than piston engines, and the rotary's fuel consumption doesn't increase with RPM as much as a piston engine does. (Most automotive piston engines are tuned to cruise in cars at about 2000 rpm, far less than a marine application cruise.)

We can supply the engines with a variety of drives -- inboard, jet, surface drive, and we have adapters for common sterndrives.

Please visit our much more detailed website at www.rotarypowermarine.com!

Best regards,
Jon Lauter
Rotary Power Marine Corporation
516-656-5685

[tom28571]

Jon,

I guess that it was your engine that was at the IBEX show.

What would be a realistic cost for the total installation of the unturbocharged version? Do you have any actual fuel use figures for both propeller and jet versions?

The rotary does seem well suited to use in boats.

Here are some MSRP's. Of course there are OEM and trade discount programs available, and depending on the buyer's location those prices would be provided by our distributors.

175c (nat. asp, carb) = $6855 bobtail, including fresh water cooling, not including raw water pump (as jets and some sterndrives don't use the pump).

175c inboard, with Hurth 45A transmission, fresh water cooled, including raw water pump, transmission cooler, rear mounts, all assembled, painted and ready to install = $9995

240Si (supercharged, digital engine management) = $10995 bobtail, equipped as above.

240Si inboard with Hurth 45A gear, as above, = 13,995.

We also offer complete surface drive packages with either engine in singles or twins (Harry Schoell's PSI drive), a small gearbox specially for jet drives, and we have various adapters for outdrives. Please call us for pricing on these at 516-656-5685.

Fuel economy:

175c cruise data we have includes:
3.5 GPH (a large wooden displacement hull)
5.5 GPH (Kenner Vision 18 bay boat with PSI drive, top speed 50mph)
7.0 GPH (per engine, Pacemaker Wahoo 26 twin. Top speed 29kts)
6.5 GPH Ebbitide RX-19 jetboat
WOT fuel consumption is about 16 - 17 GPH.


Very limited data for the 240Si as yet. WOT is about 25 GPH. Cruise is expected to be very economical, because the engine displacement is the same as the 175c, and at cruise the engine will be operating at a very efficient point -- just below the onset of boost. The engine management system is optimized for economy at part load conditions. Initial testing of several boats showed impressive fuel consumption, cruise at 6 GPH and below, but more data collection is required.

Jon Lauter
Rotary Power Marine Corporation
516-656-5685

[andreirochian]

thanks for suggestions.i shall carefully look into each.
what I m actually trying to do is a cold molded mahogany over fiberglass hull design, kind of modern streamlined line using classic materials, to accomodate 4 and go pver 30 knots.
soon renderings on www.yacht.ro

Here are some MSRP's. Of course there are OEM and trade discount programs available, and depending on the buyer's location those prices would be provided by our distributors.

175c (nat. asp, carb) = $6855 bobtail, including fresh water cooling, not including raw water pump (as jets and some sterndrives don't use the pump).

175c inboard, with Hurth 45A transmission, fresh water cooled, including raw water pump, transmission cooler, rear mounts, all assembled, painted and ready to install = $9995

240Si (supercharged, digital engine management) = $10995 bobtail, equipped as above.

240Si inboard with Hurth 45A gear, as above, = 13,995.

We also offer complete surface drive packages with either engine in singles or twins (Harry Schoell's PSI drive), a small gearbox specially for jet drives, and we have various adapters for outdrives. Please call us for pricing on these at 516-656-5685.

Fuel economy:

175c cruise data we have includes:
3.5 GPH (a large wooden displacement hull)
5.5 GPH (Kenner Vision 18 bay boat with PSI drive, top speed 50mph)
7.0 GPH (per engine, Pacemaker Wahoo 26 twin. Top speed 29kts)
6.5 GPH Ebbitide RX-19 jetboat
WOT fuel consumption is about 16 - 17 GPH.


Very limited data for the 240Si as yet. WOT is about 25 GPH. Cruise is expected to be very economical, because the engine displacement is the same as the 175c, and at cruise the engine will be operating at a very efficient point -- just below the onset of boost. The engine management system is optimized for economy at part load conditions. Initial testing of several boats showed impressive fuel consumption, cruise at 6 GPH and below, but more data collection is required.

Jon Lauter
Rotary Power Marine Corporation
516-656-5685

Hi Jon,

I hope you do not have a good sleep........

Originally Posted by andreirochian

I do not have expereience with rotary engines, but I ll do some research,
regarding the small jetdrive it seems to me the customers that we are targeting tend to be cautious to "new" stuff but I ll look also into this option

Hi Andreirochian,

Would you please be very careful with Jon Lauter.
He takes money and DO NOT delivery engine...
My e*mail address: aneymark@tiaa-cref.org