Dp... 1:1.78 vs 1:1.95 (heavy boat)

[Diver!]

I have both. Which would you use and why?

454 and probably about 7k lbs boat. Looking for best cruise speed economy (20 knts?) but a good hole shot would be nice too.

Thanks
Andrew

 

[beermak]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

im not 100% sure but ull need a 1.51 for a 454!

in order to play a little ull be doing that with the prop but i wouldnt use a high ratio drive.

 

[RogersJetboat454]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

im not 100% sure but ull need a 1.51 for a 454!

in order to play a little ull be doing that with the prop but i wouldnt use a high ratio drive.

He's got a Duo Prop drive. Gear ratios aren't going to be comparable to a single prop drive.

 

[Don S]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

After looking at your other post where this boat was originally twin 454's, I would probably go with the 1.95.

Have no idea how fast you will go or anything else, when you go from 600 hp to 300, you may not even get on plane.

 

[GilligansIsland]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Diver! I am looking for a good 1.78 EDIT
Thanks.

 

[GilligansIsland]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

I guess if you're interested in selling it you can reach out to me here.

I put my cell number in the last and if that broke the rules, I apologize.

 

[Don S]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Just send him a private message.

 

[Diver!]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Volvo says use the 1.78 with 454. Proptesting will be fun. These hulls actually had a single 5.7l as a option(also single 454) so I'm somewhat confident it will plane. Sorry not selling anything. Keeping extra drive as spare.

 

[Don S]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

I know Volvo says 1.78 as the normal drive for most cases. But you have a boat going from twins to a single 454, you may want the 1.95. You have both, give them a try and see what you like best.

 

[GilligansIsland]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

That's interesting. Would characteristics would you expect to see out of each drive if they are propped correctly?

Why does Volvo recommend one over the other?

 

[Don S]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Why does Volvo recommend one over the other?

Trial and error real life testing after doing all the engineering on paper first.

Gear ratios is what keeps props in their most productive ranges. When you get out of those best ranges for the props, then you loose either hole shot or top end.

 

[Diver!]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

I know Volvo says 1.78 as the normal drive for most cases. But you have a boat going from twins to a single 454, you may want the 1.95. You have both, give them a try and see what you like best.

Exactly!
Going with the 1.78 first and will get it propped correctly, then will do the same with the other. I'm very lucky to be in this situation.

 

[Don S]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Exactly!
Going with the 1.78 first and will get it propped correctly, then will do the same with the other. I'm very lucky to be in this situation.

Especially if you have enough prop sets. Keep them as sets, don't try to mix them. It won't help a bit.

 

[Diver!]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Trial and error real life testing after doing all the engineering on paper first.
.

Bingo!

I can play paper games all day, but the only way to do it is sea trial and prop match.

Any one in here have access to volvo Mvp prop selector program? I'd like to get a recommended starting prop and adjust from there.

 

[Diver!]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Especially if you have enough prop sets. Keep them as sets, don't try to mix them. It won't help a bit.

I have 2 sets of b7s :-( probably too much prop for either drive

 

[Don S]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Any one in here have access to volvo Mvp prop selector program?

Might post over in the prop forum and see if someone does.

 

[Diver!]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

Especially if you have enough prop sets. Keep them as sets, don't try to mix them. It won't help a bit.

Might post over in the prop forum and see if someone does.

Great idea, thanks again.

 

[GilligansIsland]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

I have 2 sets of b7s :-( probably too much prop for either drive

I've had the Bayliner Contessa in Sunbridge and Command Bridge models. B2 or 3 is the right prop for that boat depending on load, but B2 is the safe bet. That boat was just under 7000lbs.

Hope that helps.

 

[Diver!]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

I've had the Bayliner Contessa in Sunbridge and Command Bridge models. B2 or 3 is the right prop for that boat depending on load, but B2 is the safe bet. That boat was just under 7000lbs.

Hope that helps.

Yes it does! Thanks so much!

 

[Tail_Gunner]

Re: Dp... 1:1.78 vs 1:1.95 (heavy boat)

A duo prop and a 454 wont push you up...What type of trim tabs do you have or are you using tab's? Just a thought do you know your rpm level's when you at full power or wide open throttle? You may want to explore that along the way..maybe the first order of business..can that engine reach 42-4600 rpm?