Prop size (Page 2 of 2)

Right, Eegum....you have a Rogers Contessa, and the engine sits differently altogether, doesn't it, and you DO have different cockpit lazarette locker configuration so, that explains it...but it's still alot of engine?!  How do you find it?! Can you do 10 k?! hee hee

Well, I'll be headin' that way for the Jester Challenge in 2010....anyone else?! Andrew?!?!  ;-)
Yup, we get some good currents here too (Vancouver, Canada, Mark knows!)...I learned real fast how to steer in reverse when the current caught me the very first time...now when it gets me I work with it, however, always in reverse...she steers much better, but it gives the heart a good workout, and it's even worse when everyone watches..."what's that dumb woman doing facing the wrong way...", I've learned to use my lines too while leaving the dock ("please don't touch my lines, I'm doing fine on my own, really, but thank you very much"...lots of dirty looks, I tell ya!...I learned I can turn her almost right out just by springing her stern against the dock, and bursts of power...and my prop is the little 12x9 two blader...lots of room for me to work on the prop!

Well the prop came in the mail in time for Xmas and I'm not sure whether to put it on the boat or place it on the mantle, it's beautiful.  The prop make is a Michigan Wheel, and thanks to "Uncle Dave" the price, well to add to the other post-topic, it fits into my stocking.  Down here on Lake Erie we don't get too much in the way of currents or tides but we do get serious Lake Erie chop, waves are square and very close together.  This was the second year for me and my Contessa and I still can't believe how well she handles the rough stuff.  Happy Holidays to all.

I would like to get a few opinions regarding prop size and pitch for my Contessa.  The engine is a new Yanmar 1GM10 with an 11"x6 3 blade prop.  Maximum RPMs is about 3000 and while it pushes the boat along, it seems to be lacking in speed.  I've been checking the Tech site and other sources and have seen ranges of 12"x13 and 12"x8.  I sure would appreciate any input.  The boat was pulled for the winter yesterday so I've got the time.

I have minimal exposure to this but when I was on Dennis Gray contressa last year, he stated that when he was in the yearly race across the Mobile Bay, he could sail faster because of his 2-blade then the other contessa in the marina that had a 3-blade.  If you sailing, the extra blade does create an extra drag but if you need speed or power 3-blade maybe better.

THanks, need the power in these currents, but what size and pitch would you recommend?

Hey Kristin!  I have come to the conclusion that finding the right prop ends up being a roll of the dice.  Like you, I have been struggling to find just the perfect prop for my new 1GM10.  After doing a good bit of research and reading all the comments on this board, and talking to several prop experts, I finally decided an 11RH12 3-blade by Michigan Wheel was the prop for me.  In our sea trials this week with the new engine and prop, and with two people on board, we were pushing along at 4.5 to 4.8 kts into a pretty stiff head wind.  With no wind, we were doing 5.0 to 5.1 kts.  This was at 2900 rpm.  I am working to find another 500 rpms or so from my engine.  If I can get my rpms up to around 3500, then that should edge my boat speed up a hair more.  I am not displeased with my prop selection, but I am thinking maybe another prop might give me a touch better performance.  I won’t truly know until I work with the one I have for a while in a variety of conditions.  In the end I had to just take the plunge and get the prop I felt was most correct.  I thought if I didn’t nail it the first time, it wasn’t gonna be the end of the world.  I figured there would be plenty of opportunity during future haulouts to spend a few more of my precious presidents to change it out for one that hopefully by then I knew would be a perfect match.  We battle some pretty potent currents here on San Francisco Bay….probably not as stiff as the ones that rip through your area between islands…so I understand fully what that extra knot of push can mean to you in terms of safety and maneuverability. Good luck to you as you make your choice.  You'll probably land the perfect prop the first time!  The 11x13 sounds like a good choice.  Be sure to let us know how it turned out for you.

Kristin

I have a 12rh13 two blade and I'm still not that satisfied with mine.. and we don't have that much current to deal with here where I'm at... maybe I just don't have the RPM's that I need... this is an issue that I'm certainly hoping to resolve...
of course beings it's out of the water and it wont be back till May some time... it will be a long wait.

I've even given thought to a Max Prop... although I might have to sell off one of my children... I find that I have very little control in reverse and with a good head wind I'm just not going anywhere fast.

Thanks Mark for the info... will stay tuned

Update on sea trial of Yanmar 1gm10 with old two blade  12x9 prop...we decided to repitch 1".  What happened was that we couldn't get out of the piers, in reverse with side wind...had to get towed after getting banged around alot...prop guy said, "of course you couldn't get out in reverse, it is a two blade"!  However once we got turned around, we were able to go over 7 knots at 3200 rpm....what????  Wasn't sure if that was ok, so backed down until we do the heat check from where the exaust comes out of the head. Oh, wow, how she cut through the water, I am sooo impressed, never having been on a Contessa.  Will switch to the new mainsail and go again!

Kristin, I too have a two-blader and an old, rebuilt Farymann....and I too can zip through water at 6k or more...and yes, with side wind, tough to get out unless you back right into the wind...even if that means backing all the way out of the marina...face the rear, and you will move the tiller back and forth a  little bit, due to prop walk, wind, and current....keep your eye on the bow too, but you will find it much easier to back out.  Use your lines too, to "warp" her off the dock.  Keep your boat hook handy, and pretend no one is watching, hah!  Don't let people help you unless you tell them what to do, or you are sure they are experienced, or else they will simply grab your shrouds and try to pull the boat!! 

Jim, way to go on the new prop...ha ha on the waterskis! ;-)