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Messages - kurt

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I have to admit to be scratching my head on this one but I got 2800 with 7 knots of wind on the beam in flat water heading back into the marina.  The same rpm as with the mainsail flogging motoring directly into 19 knots of wind with small chop.  (I did see 3000 one morning with no wind in flat water.) This similarity of rpm has me leaning towards declaring success and moving on to the next boat project!


Yes - did pick up ~ 1/4 to 1/2 knot.  I cruise at around 2200 - 2400 btw now at ~ 6 knots.  Of course, in my harried planning forgot to document the old prop velocity by rpm so this is bump in velocity is approximate and based upon a rapidly fading recollection.

Hello All,

Based upon vendor recommendation, I went with a 10" pitch for the 3 blade flexofold 15" diameter for my '88 25xp.  (I did secure their agreement to go down to 9" pitch at nominal cost if I desired to do so.)  Also learned during installation procedure that I previously had a fixed, 3 blade 15x10" Michigan Sailer prop.  I have not calibrated by tach which makes the following data suspect but I have the original alternator and the numbers seem to be in the right ball park. 

So, my previous prop at load got up to a max rpm of ~3000. 

The folder that I just added now gets up to ~2800 rpm.  Further tested it last evening evening with mainsail up, motoring directly into a 19 knot breeze with small chop, slack tide and got 2800 rpm.  May be getting a small amount of grey smoke at this rpm but not sure.  Finger across stern did not find any soot when back on the dock but only ran for a couple of minutes at max rpm.   

Any thoughts regarding these results?  I'd like to see 2900 or 3000 but am leaning to staying as is with the 10" pitch and avoiding the hastle of replacing blades.  9.5" pitch would probably be perfect!

Thanks in advance,


Main Message Board / Re: manual bilge pump
« on: June 02, 2008, 08:46:01 AM »
I am not sure about your 1990.  This service kit did the trick for my '88.

Gusher Titan Service Kit|51|299222|84462|316440|315120&id=161316


Main Message Board / Re: Water lift Muffler
« on: May 22, 2008, 03:19:06 PM »
I had a similar problem on my '88 this year regarding the leaking hump hose. 

In my case, I came up with the clever idea to replace the standard hose clamps with some of those solid steel band style hose clamps thinking more torque was the solution to this leak.   It was but indirectly -- I ended up torquing the clamps so hard around the hump hose that I  crushed the tube that went into the muffler.  Maybe as a result of the crushing, I was able to pull/rotate the tube cleanly, as one piece, out of the muffler.  This fiberglass tube was glued or fiberglassed into the box as a part of the standard muffler manufacturing process.  This made the repair easy and I had the shipyard epoxy/balloon a standard pipe type fitting with pipe thread (down) barb side (up) very cleanly back into the hole.  Althought I wouldn't recommend this as the "plan a" over the rebuilds noted, it may be a decent interim step to try prior to ordering a new muffler.  I'm up to over 50 hours since the repair with zero signs of cracking at the fitting/muffler joint.


Thanks for all of your comments.  These are helpfull to my decision making process.

I have several additional followup question for Catalina 34 owners with 25xp engine with 2:1 transmissions: for the 15 x 10" flexofold 3 blade users what is your cruise speed at ~2300 rpm and does your engine rev past 3000 rpm easily/cleanly?    9" flexofold 3 blade?  10" Gori 3 blade?  9" Gori 3 blade?  (I know the Gori's have the "overdrive" so assume that is cruise mode.)

Thanks again for any comments.


Hello everyone,

I've queried my mechanic, potential suppliers,  and this group and now have some conflicting data points regarding pitch I'm working to sort out.

Specifically, I'm considering adding a 3 blade folder to my '88 C34 w M25xp engine (2:1 ratio I believe) and have received several recommendations for pitch - 15" is consistent for diameter.  (I do not know the pitch on my current 3 blade fixed.  It does rev to > 3000 rpm panel tach view.)  I understand from this board that the standard C34 3 blade for the XP is 9".  My mechanic recommends 9" for the 3 blade folder.   Folder vendor A recommends 10" (but 9" is ok.) Folder vendor B recommends 9".    I'm leaning towards the 3 blade 9" as the conservative choice that has little downside as far as I understand it.

Does anyone have any data suggesting what the velocity difference at ~2300 rpm would be between the 9" vs. 10" pitch of a similarly designed prop in flat water?   Would flat water provide the worse case delta?  Is this loss of velocity for given rpm the sole downside of the 9" pitch?  Should I expect to continue to get to >3000 rpm with a prop of 10" pitch on the 25xp in flat water?   In all sea conditions?   Any thoughts or advice here?   

Thanks in advance for offering any data or experiences here.


'88 C34

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