Jersey Speed Skiffs, engines, gears, caviatation etc.

**User Name** · 03-17-2023, 06:13 PM

Hello all,

I'm gaining interest in obtaining a speed skiff hull or a complete speed skiff. I realize these things are few and far between so I have a few "what ifs" going on in my mind. I'm a real rookie when it comes to the technical part of boats. I'm more of a car/motorcycle guy. My online research indicates that in-board boats do not have transmissions (like a automobile transmission) but somehow have gears that reduce the spin of the propeller shaft. Meaning the prop shaft is spinning more slowly than the motor crankshaft to make sure the propeller intake force and thrust are in proper order. Please let me know if anything I say is incorrect. I'm trying to generalize the whole thing.

What do you call this type of gear mechanism? I read an article (forgot the link) that talked about them having gears and them not having gears. It contradicted the hell out of itself which got me even more confused.

Okay so my question is: If a speed skiff typically has a 289 or 305 cubic inch V8 what mechanism is used to keep the prop shaft slower than the engine crank shaft?

If I found a speed skiff sans a v8 then would it be tough to replace the v8 with a Volvo redblock engine? I now this sounds silly but I have a limited budget and a Volvo redblock in great shape. I'd like to know if this gearing mechanism will fit a redblock or will I really need to have a Chevy V8 in it. I'm not concerned about engine mounts. My gut says any speed skiffs available with reliable V8 are going to cost a pretty penny and I'd rather not try one with a V8 that's been behind the barn for the last 30 years.

Please help me out with this guys. Thank you!

Also, are there any Jersey Speed Skiff manufacturers still in business? Youtube videos of them racing make me think that are. Please let me know. Thanks again.

**rgsauger** · 03-17-2023, 11:42 PM

Hi bud. Welcome to the forum.

so an inboard boat does have a transmission but it is simply a forward and reverse unit and does not shift through three or more gears like you do in a car. Typically, there is also a gearbox that is tied to this transmission that changes the angle of the driveshaft to go down steeper than what the Motor angle is mounted at. There are different ratios that gear the prop shaft relative to the crankshaft of the engine. This depends on what the intended type of propeller and what rpm and speed that it needs to turn at. Some of them are simply one to one.

Chevy is Chevy when it comes to bolt patterns and that type of thing. You should be able to unbolt one Chevy V8 small block and bolt in another one. The Volvo red motors are simply GM motors the Volvo has marinized.

**User Name** · 03-18-2023, 09:10 AM

Thank you very much! I had totally forgotten that the Volvo red block was also used as a marine engine. I have one in my Volvo 245 car that will soon be coming out. The idea of placing it into a boat now seems less crazy to me.

I'm hesitant to post a wanted ad for a speed skiff in the classifieds section at this point but if someone here knows where I may find one on the east coast then please shoot me a message about it. Thanks

**rgsauger** · 03-18-2023, 06:37 PM

When you say Volvo red block motor, is this a 4 or 6 cyl or?…. I know that Volvo painted their marinized gm motors red but not sure that all red motors are marine in nature, per se. the main thing on a marine engine is that things like alternator and dizzy are marine rated to be explosion proof, non sparking. Carbs have J tubes that flood into the carb, not down the outside of the motor. Cams are usually mild to prevent water reversion and exhaust manifold is water cooled with water injection into exhaust to cool things down. Do a little digging. Lots of info on this. Is a speed skiff like a cracker box?

**User Name** · 03-18-2023, 07:19 PM

Originally Posted by rgsauger

When you say Volvo red block motor, is this a 4 or 6 cyl or?…. I know that Volvo painted their marinized gm motors red but not sure that all red motors are marine in nature, per se. the main thing on a marine engine is that things like alternator and dizzy are marine rated to be explosion proof, non sparking. Carbs have J tubes that flood into the carb, not down the outside of the motor. Cams are usually mild to prevent water reversion and exhaust manifold is water cooled with water injection into exhaust to cool things down. Do a little digging. Lots of info on this. Is a speed skiff like a cracker box?

Funny you should say that because I just read about a cracker box about 20 minutes ago! Thanks very much for your input. I may go ahead and order me a copy of this https://www.glen-l.com/inboard-motor-installation/ so I have a better understanding of all this. I'd rather not bug you guys too much.

When I'm talking about red blocks I mean theses: https://en.wikipedia.org/wiki/Volvo_Redblock_Engine
I thought they were/are all 4 bangers but I may be mistaken. Since some of these were used as Volvo Penta marine engines I figured the one from my old wagon may be an option but perhaps not. May have to take the KG Trimning 004 performance cam out if it gets put into a boat. That and a lot of other stuff apparently will need to be changed.