TW28 propeller

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Corto Maltese
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TW28 propeller

Post by Corto Maltese »

Finally, I'm going to buy a propeller now for the TW28. But... there's no exact answer and I'm a little bit confused.
I have a Beta Marine 43hp (Kubota) 2800rpm engine with TMC60 (2.54) and a Python Drive in front of the 35mm axle. Now, Jacques proposed a long time ago a 17"x13" propeller for a similar engine and transmission, but the dealer suggests to me 19"x17". I wanted a 19" 3-blade propeller as there's enough room.
I checked different online pitch calculators and I'm even more puzzled. The data ranged from 19"x11" to 19"x14" and one calculated the same 19"x17" dimensions as the dealer offered. So, maybe this last dimension could work.
But I would like also to ask for real experiences from builders and practical people as obviously there's no hard science working here. Especially because the hull of TW28 with box keel is not common.
Wish you nice summer on your boats or successful boat building.
Dario


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fallguy1000
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Re: TW28 propeller

Post by fallguy1000 »

How much clearance 19" prop? There are clearance guidelines as well iirc.
My boat build is here -------->

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Corto Maltese
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Re: TW28 propeller

Post by Corto Maltese »

fallguy1000 wrote: Thu Jun 23, 2022 9:48 am How much clearance 19" prop? There are clearance guidelines as well iirc.
Enough, therefore I went for 19". There's 60mm down to the foot of the rudder (skeg??) and even more up to the hull.
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TomW1
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Re: TW28 propeller

Post by TomW1 »

Dario, a 19" diameter sounds good. Now for pitch, as you go up in pitch you add speed but put stress on the motor. When you prop a boat you want a prop that will reach max rpm's and then will cruise at it's most functional fuel effeicency. I do not believe the 19x17 would be right for the weight of the TW28 but try it and see., you need to max rpm's with it. A lot depends on rake and pitch also. With a TW28 you want a prop that is designed for thrust not speed. Maybe the other TW28 builders will see this and chime in and tell you what motor and prop they have. See Broomsides post down in Builders Power Boats, he uses a 19 x 13 prop for his 44HP motor that is why I said the 17 pitch sounded to much. He can give you more information on his prop.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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