Gear Ratio question

Bill

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Buying a 230 yanmar rated at 3300 rpm.. I have access to a 1.5:1 zf 63a.. It's going to be turning a 20-22" prop .. 1.5" shaft..

Will the tranny work for a mostly lightly loaded boat?
 

Bill

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[YOUTUBE]HjKaOSaOmGI&feature=youtu.be[/YOUTUBE][YOUTUBE]j3xJmECPx8g&feature=youtu.be[/YOUTUBE][YOUTUBE]T6NVdS6ytd4&feature=youtu.be[/YOUTUBE]



Sea trail today down the cape.. Was a little cold

http://youtu.be/HjKaOSaOmGI
 

captainlarry84

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Buying a 230 yanmar rated at 3300 rpm.. I have access to a 1.5:1 zf 63a.. It's going to be turning a 20-22" prop .. 1.5" shaft..

Will the tranny work for a mostly lightly loaded boat?
Sorry Bill you will not turn a 20 X 22 with a 1:5 gear in a 27 foot DE Not even close. You will need a 2:0 gear for sure.
 

Bill

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Ok. Thanks Larry.. I'm not set on a prop yet.. Still no way right ? So I should be absolutely looking for a 2:1? I'm pushing it cause it's a basically new 63a for $600.. It is what it is I want to do it right so if I have to pass I will
 

Keelboater

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Bill - why was he pulling the Yanmar? Was this the one posted here? It sounded nice in the vids.
 

captainlarry84

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Ok. Thanks Larry.. I'm not set on a prop yet.. Still no way right ? So I should be absolutely looking for a 2:1? I'm pushing it cause it's a basically new 63a for $600.. It is what it is I want to do it right so if I have to pass I will
correct you max wheel with a 1:5 would be about a 17 X 17 plus or minus 1"
 

Bill

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Yes it is on an outdrive right now I have the bell housing on the way. The seller is a member on here who is putting a outboard on it. I think it's a 23 formula , old school one that looks like a seacraft or fish nautique ..i had it gone over by the yamnar dealer who is gonna adjust the valves and go over it for me
 

Toolate

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Will you be going with the same diameter prop you had before? What engine/gear did you have before?

You been watering the TJ? Sounds like its growing.
 

Bill

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Not sure about prop size I gotta make some phone calls before I decide. I have different people telling me completely different things
 

petrel

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Bill, Yanmars spin really fast, so I would think matching reduction gear ratio would be closer to what you'd have for a gasser than what you might think at first. Just look at your engine rpms and do the math to see what the shaft speed would be. It would be whirling w/ a 1.5 to 1. I would think you'll need to slow yours down more than Bill D, as his engine is turning 2600 WOT. What reduction is going w/ his 6BT?
 

BillD

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If I recall Bill's 25 had a 460 Ford with a 2.91:1 Borg Warner 72C gear swinging a 20X20 three blade.
I'd also consider using a 2.5:1 gear with the 230 Yanmar and a 22 inch prop.

Petrel,

Cummins 6BTA 330/370 idles @ 600 rpm...1.5:1 ZF63A is a good gear with a 20X (22/23/24 pitch) prop. Maybe too much hp purchased overall but a solid 18-19 knot cruise @ a "quieter" 2100 rpms.

The 6BT 210/220 idles @ 700 rpm. A 1.5:1 gear with a 20X 20/22 prop might be "jumping a bit" in and out of gear and give ya a too fast idle around the harbor.
2:1 gear would be a good choice for the 6BT but you'll be cruising up @ 2400 @ a 18-19 knot cruise.

Many options available...many trade offs.........as always in boats. :D

Now a factor to consider, Bill's boat will be ??? 27.5 ft. ???

Maybe a bit easier to push than the "stock" 25 footer.
 
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Bill

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Billy that gear that I have attached to soon to be 460ci mooring is a 1.88/1..I thjnk the wheel is 18 or 19..
 

petrel

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Bill D,

What ratio are you actually going to use w/ the 6BT for your boat? And what size prop to do you expect to turn on your boat? Couldn't even tell if you had made you mind up by what you just posted, but I figured you had it all figured by now.
 

Bill

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Talked to Terry Jason on the phone for a solid 15 seconds . Before I could even get the question out of my mouth he said 2.5:1 with a 22" square prop. Whatchuguysthinkofthat?
 
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