Martec Folding Prop Pitch

[greese]

I am considering replacing my fixed 2 blade RH 15" x 12p with a Martec RH 15" x 14p folding prop. Will this work on my 1986 C-34 with the stock Universal M25 engine drivetrain.

[Dave Spencer]

Greese,
I think a pitch of 14 will be far too much for your engine.  You will be significantly over-propped and won't be able to achieve the engine rpm required for efficient operation.  Expect significant smoking from the engine.  Search the forum and Tech Wiki to see what others have done.  Better yet, the C34 Tech Notes have some good information in them if you are a member of the C34IA.  Membership is a bargain - rare for anything to do with boats!

[greese]

Thanks for the input. Would it work to go down to a RH 15" x 9 p?

[Noah]

Every prop is a bit different. I haven't heard much about Martec since I experienced the rattle of one on an IOR race boat I sailed back in the day.  If you are set on Martec, I would recommend you check with their customer service folks — and go with their size recommendation—contingent upon their assurance that they would accept a return or re-pitch the blades, if they were not a sufficient match to your boat/engine.

[Robert Mann]

Greese, I have a Martec folding prop, 2002 vintage, and I would recommend that before you buy one you find a boat with one fitted and motor with it.  One of my next projects is to get rid of the folder, and move to a Campbell Sailor.  Firstly, it is noisy and it rattles at low speed despite having been rebuilt with virtually no hours, approx 350, on it.  Secondly the engine needs to idle at approx 600 rpm, which is too low a speed for my liking.  A much higher speed results in a tremendous force on the shaft when engaging the transmission.  If you are maneuvering in close quarters be especially careful that you allow the engine to achieve the low idle speed before shifting from ahead to astern, as  the "snatch" on the drive line is very high at above lowest idle.  Previous owner replaced existing shaft with stainless steel, after bending the original.  The letter explaining the warranty decision, from Frank Butler, quite clearly outlines the dislike of folding propellers.  When I finally get out of quarantine I can send you the details on mine.  As you can see it isn't my favorite accessory item!

[scgunner]

Greese,

Unless you're racing the boat what's the point of installing a folding prop? When I raced my boat I used a folding prop, after the race I replaced it with the good old reliable Sailor. A stock properly set up C34 will motor around 6 knots, under sail depending on sails, rig, and conditions you should get 7+ knots. The guys who designed this boat, motor, and prop combination to give the best all around performance probably knew what they were doing. When you're bow to bow on a race course a folding prop makes a big difference the rest of the time it's hard to tell what kind of prop is on your boat.

[Stu Jackson]

Fleet 1 on San Francisco Bay has, over the past 25 years, developed a very fair PHRF rating for their C34 One Design fleet.  I trailed a three bladed bucket around from 1999 to 2006 back when I raced and got a very fair rating adjustment.  Seems to me that if you're racing, there should be fair adjustments for slightly different gear on different boats.

[scgunner]

The PHRF is pretty good at leveling the playing field, or should I say sailing field, as you know there's a huge difference between a stock cruising 34 and a full race 34. We've often had a laugh about some particularly fast boat in our class, saying if looking ahead if we could see him on the horizon we were beating him.

[Stu Jackson]

>>>>>>>>>>>>
as you know there's a huge difference between a stock cruising 34 and a full race 34.

We've often had a laugh about some particularly fast boat in our class, saying if looking ahead if we could see him on the horizon we were beating him.

Perhaps the ratings adjustments would provide a list of those differences (attached is a PDF):
-- jib size (small jib 110 or less)
-- furling or non furling w/ height of jib tack 8" or more off the deck
-- fixed or folding prop (fixed 2 or 3 blade)
-- wing keel
-- tall rig

That said, there are really not a whole lot of other differences between stock and what you call full race C34s.  At least based on Fleet 1's experiences and they are THE racing group for our boats.

Laughs I understand.  But with our ratings, there was only one race where I remember having someone sail by us but we won on time.

Remember, these were ALL one design C34s in our races because we had enough C34s for our own starts.

It could well be different in mixed groups, but then that would mean the ratings weren't quite good enough, or that that's what PHRF is there for but they mixed significantly different types of boats together (someone doing a horizon job on you).

[scgunner]

Having an all C34 fleet would be really cool, although there are a lot of C34s in SoCal we never really had a fleet, so the racing I did was always against a mixed fleet, making the PHRF ratings all the more important.

As in any form of racing there are always guys who take it very seriously, even on Wet Wednesdays and beer can races. The racing C34s I'm talking about have everything on your list plus; a full inventory of racing sails, foil headstay, hydraulic backstay for sail shaping, completely upgraded deck hardware and lines, freshly faired bottom, weight reduction to the tune of 500+ lbs, and a bunch of other stuff I can't think of right now.

I think the horizon boat we were laughing at was a full race Schock 35, although now that I think about it maybe we shouldn't have been laughing at a guy who was a mile+ ahead of us.