Prop Size for T-37C

stupippin44 · **Joined:** 26 Jul 2008 11:47 **Posts:** 4

I own (since 9/08) a T-37C Hull #280 w/50Hp Westerbeke, I want to replace my 2 blade folding prop for a 3 blade fixed, can anyone out there give me the recomended prop size? (1"x?x?)
Thanks for any help. stupippin44
St. Pete, Fl.

sundog · **Joined:** 15 Aug 2008 18:14 **Posts:** 21

stupippin44 wrote:

I own (since 9/08) a T-37C Hull #280 w/50Hp Westerbeke, I want to replace my 2 blade folding prop for a 3 blade fixed, can anyone out there give me the recomended prop size? (1"x?x?)
Thanks for any help. stupippin44
St. Pete, Fl.

Sorry I can't give you an exact size recommendation...but something to seriously consider is clearance between the blades and the boat bottom. Given the way the propshaft is oriented on a T37 you are very limited in clearance especially when going from a folding prop to a fixed blade. The reason is that the folder will essentially extend the length of the propshaft giving you additional bottom clearance.

The problem is that when the prop swings too close to the boat bottom you pick up vibration and prop effeciency suffers.

I believe the standard prop was a 16" X13" two blade and it's generally agreed that is too much prop. I would seriously consider a 15" or even a 14" fixed three blade. But I don't have any data to back that up.

By they way, if you have a W50 your continuous horsepower rating is 41, not 50. But you will never get the rpms up high enough if you are swinging a !6"x13" to get to the top of the horsepower curve.

Hope that helps.
Mike Barich
S/V Sundog
T37 #207

stupippin44 · **Joined:** 26 Jul 2008 11:47 **Posts:** 4

Mike;
Thanks for the reply, I agree about the clearance from the hull to prop as this will not only cause vibration but cavation and destroy the prop. I'll keep working on this and hopefully come up with something close enough that if needed I can re-pitch (2" Pluss or minus).
Regards >>>STU<<<

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

I have a 17 inch three blade feathering prop on my T37 with no vibration or cavitation problems. It will matter how long the shaft is as this could make a difference in clearance--I might have a slightly longer shaft as I have done an engine swap and I think I might have added an inch to its length. But I agree that the standard two blade prop was grossly overpitched for some reason. I believe that you will discover that you want to swing the biggest prop you can without cavitation and have it of the proper pitch. David Gerr's Propeller book is very much help. If I remember correctly, you need to have about 1.6 inch of clearance from the tip to the hull based on his calculations. Have you considered a feathering prop? I got more than a half knot increased sailing speed over a fixed 2 blade and it stopped that vicious walk when backing down--though the walk can be helpful in some cases.

stupippin44 · **Joined:** 26 Jul 2008 11:47 **Posts:** 4

I agree that the feathering prop is probally the best choice but the cost is around $3,000.00 for a good one. I am upgrading the boat from inside to outside and cost is certainly a major consideration. I apreciate the information and I have certainly become more informed by you guys out there who have owned the Tartan 37.
Thanks Again >>>STU<<<

sord · **Posted:** 16 May 2009 06:29

I was having a lot of problems in reverse and have just installed a KIWI feathering prop . I am due to be launched next weekend and will let you know how it works out. I have heard from other Kiwi prop owners (one a Tartan owner) and everyone without exception loves it.
Best of all it cost under 1/2 what a bronze prop cost ($1300) and came with an extra blade Very Happy

. My neighbour hit a rock with his bronze prop and had to buy another

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

My feathering three blade is an Autostream made in Australia and sold and serviced by Martec (who were very helpful with installation advice and setting the pitch). I think it cost about $1700 in 1997 and has been absolutely great for several thousand miles. I second the idea that bronze props like Maxprop, despite their incredible marketing efforts, may not be ideal (we used to think we needed bronze shafts as you will recall and stopped that for some reason). I ran into two folks on my trip through Central America who had Max props and had problems when they struck something in one case and picked up a poly pro line in another. I picked up a poly pro line in mine off Miami and it sheared all the bolts on my coupling and pushed my cutless bearing out of the strut--but no damage to the prop. I know they are expensive, but the difference in sailing efficiency and motoring efficiency (especially with one that you can adjust pitch with the boat in the water--you can fiddle with it until pitch is perfect) would put it ahead of new sails on my priority list.

stupippin44 · **Joined:** 26 Jul 2008 11:47 **Posts:** 4

Can the Kiwi prop be adjusted for pitch in the water?
Thanks again Stu

sord · **Posted:** 21 May 2009 20:43

Yes. Go to http://www.kiwiprops.com/ for all the details Toast

cseltzjr · **Joined:** 16 May 2009 08:06 **Posts:** 236

We put a 15" Gori folding prop on 10 years ago and never looked back. Our friends with the 3 bladed Max Prop do no better under power. Under sail, the best is that there is nothing under the boat to pick up a pot. We sailed all though the west and central coast of Maine (thick with lobster pots) and never paid them any mind under sail. Plenty of push in forward and reverse. If I put on another, it will be a bit smaller. The engine (W-50) will not go over 2200 rpm with this propeller. At that the boat is doing 7.5 in flat water.

Chip Seltzer

Tartan37.com

Prop Size for T-37C

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