Big gear, Small prop -vs- Small gear, Big prop
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Big gear, Small prop -vs- Small gear, Big prop

  1. #1
    Senior Member f_inscreenname's Avatar
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    Default Big gear, Small prop -vs- Small gear, Big prop

    Got a chance to pick up a 1.3 Volvo drive to replace my standard 1.63 Volvo in my 19' Nova. One of the issues I have always had is when you get past a 21 pitch prop your selection is almost nothing. I have a 23P Solas on it now and like said the drive is a 1.63 its about as big as it gets. The only way I can describe it is it (496 roller motor and a Volvo 270 with 280 trim shield) feels heavy with the big prop. Great cruise, strong pull but.... and now that this 1.3 is available its got me thinking (just for prop selection alone).
    So here is the question.
    What is better and why (characteristics) please;
    1, A smaller gear ratio in the drive and larger prop
    2, bigger gears in the drive and a smaller prop
    A winner is just a loser that got up and did it one more time.
    1959 Biesemeyer - 4pt Hydro Drag - 2013 ACBS Winner - Best Race Boat
    1966 Donzi 16
    1967 Nova Marine - SuperNova24 - ACBS Winner - 2012 Best Race Boat - 2016 Peoples Choice & Best Non Wood
    1972 John Allmand - Nova 19
    1982 PolarKraft -Jonboat - Crab Killer

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  3. #2
    Member Dano214's Avatar
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    I don't mean to jack your thread but, Were did you get that drive cone for the 280 drive. I think it's called a speed cone? to make the lower drive section more water dynamic.
    Thanks Dano

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    Quote Originally Posted by f_inscreenname View Post
    Got a chance to pick up a 1.3 Volvo drive to replace my standard 1.63 Volvo in my 19' Nova. One of the issues I have always had is when you get past a 21 pitch prop your selection is almost nothing. I have a 23P Solas on it now and like said the drive is a 1.63 its about as big as it gets. The only way I can describe it is it (496 roller motor and a Volvo 270 with 280 trim shield) feels heavy with the big prop. Great cruise, strong pull but.... and now that this 1.3 is available its got me thinking (just for prop selection alone).
    So here is the question.
    What is better and why (characteristics) please;
    1, A smaller gear ratio in the drive and larger prop
    2, bigger gears in the drive and a smaller prop
    what rpm are you turning the 23 at what speed.It sounds like your on the right track spinning a lesser pitch faster

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  6. #4
    Senior Member f_inscreenname's Avatar
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    Quote Originally Posted by Dano214 View Post
    I don't mean to jack your thread but, Were did you get that drive cone for the 280 drive. I think it's called a speed cone? to make the lower drive section more water dynamic.
    Thanks Dano
    Had to buy a boat (that I restored and resold) to get it. Saw one on eBay just a few days ago.

    Quote Originally Posted by [email protected] View Post
    what rpm are you turning the 23 at what speed.It sounds like your on the right track spinning a lesser pitch faster
    About 5100rpm's @ 61 mph
    Strange thing is with this boat is it seems to have hit a wall. Lots of props and lots of motor changes and I just cant to get anymore out of it. Starting to think that the prop (Solas) blades are getting to big and the prop is getting to heavy if that makes since. ie; I used to have a Ultra 21P prop (that had been re pitched to something with cupping before I got it) with less motor that ran damn close to what I am now @ 5200 rpm's. I feel if I can get it back into normal pitch / diameter ranges for a Volvo it would open a whole new road for me. Just wondering if there is any drawbacks to using a bigger gear in the drive then what I have now.
    A winner is just a loser that got up and did it one more time.
    1959 Biesemeyer - 4pt Hydro Drag - 2013 ACBS Winner - Best Race Boat
    1966 Donzi 16
    1967 Nova Marine - SuperNova24 - ACBS Winner - 2012 Best Race Boat - 2016 Peoples Choice & Best Non Wood
    1972 John Allmand - Nova 19
    1982 PolarKraft -Jonboat - Crab Killer

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    Senior Member GT Jets's Avatar
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    Blade design has a lot to do with it. That particular setup sounds close, but in all honesty a swept bade prop with a lower pitch I think would be more efficient.

    I did not do the math, but i would think a 21" pitch and the 1.3:1 drive would be more effective.

    There again, that drive design has always been somewhat of a speed killing pig (no offense)..

    Ever thought of scaring up a Duo-Prop? The gains could be stupid....
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  8. #6
    Senior Member f_inscreenname's Avatar
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    Quote Originally Posted by GT Jets View Post
    Blade design has a lot to do with it. That particular setup sounds close, but in all honesty a swept bade prop with a lower pitch I think would be more efficient.

    I did not do the math, but i would think a 21" pitch and the 1.3:1 drive would be more effective.

    There again, that drive design has always been somewhat of a speed killing pig (no offense)..

    Ever thought of scaring up a Duo-Prop? The gains could be stupid....
    That is what I was thinking with the lower pitch prop.
    I know that the Volvo is a pig. One of the reasons that I use a 270 drive (cleaner case), added a Volvo nose cone and filled in the water pick ups and started the upgrades way back with a 280T transom shield (with trim).
    I like the idea of a D/P but the props always put me off. $1500 a set is insane. I have a wall of props from all the boats and from changes to the 19 over the years and at 15000 a set would have stopped me from ever owning a boat. lol. Also the only D/P I could use is the 1st generation being I do not want to change the transom. Not that I haven't thought of it but a Merc or newer Volvo just wouldn't look right on it (Its 40 years old and one of only a couple still on the water so trying to keep the over all look).
    A winner is just a loser that got up and did it one more time.
    1959 Biesemeyer - 4pt Hydro Drag - 2013 ACBS Winner - Best Race Boat
    1966 Donzi 16
    1967 Nova Marine - SuperNova24 - ACBS Winner - 2012 Best Race Boat - 2016 Peoples Choice & Best Non Wood
    1972 John Allmand - Nova 19
    1982 PolarKraft -Jonboat - Crab Killer

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    Default 24 Ultras

    I have both left and right hand 24 Ultras the left is known to be cupped with a replaced hub all done by Blank. The righty I know nothing about (ebay) but the hub looks to be the original but may be slightly cupped. Both are in really nice condition I would really like to sell them together. Someone with twins would love these. PM me if you are interested.

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