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Old 15-05-2014, 00:37   #1
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Prop size for a Formosa 51

Hi there, anyone have an idea what the correct prop size is for a Formosa 51 running the original Ford 120HP engine? Cheers
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Old 15-05-2014, 18:57   #2
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Re: Prop size for a Formosa 51

Three blade 26 inch diameter with 22 inch pitch and 2 inch propeller shaft diameter. There was also a 19 inch pitch. Probably for a smaller engine. Ford appeared to be the largest engine used so I would go with the 22 inch pitch as best guess.
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Old 15-05-2014, 20:31   #3
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Re: Prop size for a Formosa 51

What happened to the old propeller because a prop can get terribly bent up and a good propeller shop can make it as good as new, or even better because of the computer controlled equipment they have now for balancing and alignment.

Michigan Wheel Propeller makes a MP3 series commercial propeller recommended for sailboats (anything less than 18 knots). A 26 inch propeller will cost $1352 in their "Machine Pitch" type. They also have a "Heavy Duty" type, costs a little more, but is thicker and stronger, but probably not quite as efficient.
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Old 16-05-2014, 18:33   #4
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Re: Prop size for a Formosa 51

On my formosa 51 I'm running a 23 inch Dia with 19 inch pitch on a 1 1/2 inch shaft. Ford 120 engine and 2.57 Velvet drive. I know it's under loaded, I normally cruise at 1650 rpm at 7 knots under power. During my last overhaul I switched from the 2" shaft to the 1 1/2 as there was less than 1/8 of an inch clearance in the stern tube with the 2inch.
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Old 18-05-2014, 10:16   #5
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Re: Prop size for a Formosa 51

Quote:
Originally Posted by westwinds View Post
Three blade 26 inch diameter with 22 inch pitch and 2 inch propeller shaft diameter. There was also a 19 inch pitch. Probably for a smaller engine. Ford appeared to be the largest engine used so I would go with the 22 inch pitch as best guess.
thank you for the information. We are running a 25 inch x 20 inch pitch.. seems to run OK was just checking to see if there are alternatives some one has tried... Is there a specific calculation that you know of? Cheers
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Old 18-05-2014, 10:18   #6
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Re: Prop size for a Formosa 51

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Originally Posted by westwinds View Post
What happened to the old propeller because a prop can get terribly bent up and a good propeller shop can make it as good as new, or even better because of the computer controlled equipment they have now for balancing and alignment.

Michigan Wheel Propeller makes a MP3 series commercial propeller recommended for sailboats (anything less than 18 knots). A 26 inch propeller will cost $1352 in their "Machine Pitch" type. They also have a "Heavy Duty" type, costs a little more, but is thicker and stronger, but probably not quite as efficient.
Hi there thanks, the old prop is fine, we were just curious of others experience with prop sizes on this vessel... We are running a 25 x 20 Cheers
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Old 18-05-2014, 10:23   #7
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Re: Prop size for a Formosa 51

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Originally Posted by rcmpegasus View Post
On my formosa 51 I'm running a 23 inch Dia with 19 inch pitch on a 1 1/2 inch shaft. Ford 120 engine and 2.57 Velvet drive. I know it's under loaded, I normally cruise at 1650 rpm at 7 knots under power. During my last overhaul I switched from the 2" shaft to the 1 1/2 as there was less than 1/8 of an inch clearance in the stern tube with the 2inch.
Thanks Bob, we are currently running a 25 with a 20 inch pitch. Was just curious of others experience and looking to lower the revs but achieve the same torque for better fuel consumption... Do you know of a specific calculation that could tell you what the tolerances are for this hull and engine size? Cheers Ivan
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Old 18-05-2014, 11:25   #8
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Re: Prop size for a Formosa 51

Be sure to get a RH, right hand, propeller. Volvo I think uses LH, left hand, and of course twin propeller boats have a RH and a LH propeller.

PROPELLERS, Used, New, inboard and outboard
PROPELLERS, Used, New, inboard and outboard

Propeller repair using computer, also new propellers
Murphy's Propellers

Used Propellers, There are several 26 inch 3 blade Right Hand (RH) propellers today, but with 26 inch pitch which will decrease RPM way too much, like 1000 RPM
ebay.com
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Old 18-05-2014, 12:33   #9
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Re: Prop size for a Formosa 51

Quote:
Originally Posted by westwinds View Post
Be sure to get a RH, right hand, propeller. Volvo I think uses LH, left hand, and of course twin propeller boats have a RH and a LH propeller.

PROPELLERS, Used, New, inboard and outboard
PROPELLERS, Used, New, inboard and outboard

Propeller repair using computer, also new propellers
Murphy's Propellers

Used Propellers, There are several 26 inch 3 blade Right Hand (RH) propellers today, but with 26 inch pitch which will decrease RPM way too much, like 1000 RPM
ebay.com
Hi there, thanks again for the information. I have just found this calculator which give me the results for a 3 blade prop 26 inches with an 18 inch pitch...
Vicprop - Prop calculator for Displacement and semi-displacement hulls

Cheers
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Old 19-05-2014, 06:39   #10
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Re: Prop size for a Formosa 51

Check on the right or left hand issue, my Lehman 120/ Velvet drive is running a left hand prop. Formosa 51's can have either.
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Old 26-05-2014, 14:30   #11
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Anyone have prop size for F46

Anyone have prop size for F46, 83 HP engine?
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