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Old 08-03-2014, 13:11   #1
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From Fixed Prop to?

Vessel is CT 47 ketch, about 40,000 pounds fully loaded, 4-154 Perkins 65HP with beautifull 3 blade 17 inch fixed propeller installed, thought to be 12-14 inch pitch. We can't find a mark... Vessel motors easily 6 knots at 2000 indicated RPMs, 6.5 at 2200.

I have never ventured into any prop except fixed, although I did fix a stop on the shaft on my schooner with a two blde prop hidden in the full keel slip stream. Ensenada race. No, we did not win.

The CT can go like snot, and we have very loud prop screaming above 8 knots degenerating into shuddering. So I have to fix this. Velvet drive so far holding up OK.

If I go folding, I think Gori 3 blade makes sense. If I go feathering, anyone have an idea? The more I Read, the more confused I get, probably the residual of a college education in physics.

We are cruisers who just hate to motor, but occassionally being able to motor to protection is a priority. So I guess minimal drag first prority, then forward motoring ability next, then reliability/ease of maintenance third.

Pardon my headbanger, not so good at this posting stuff. I am normally an answer guy!
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Old 08-03-2014, 14:37   #2
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Re: from fixed to ?

Had a 44' boat, about 32,000 pounds with a Maxprop. Feathers, so little drag when sailing. Good forward power, and great backing ability. Adjustable so it can be set for a particular boat and engine. Mine needed a haulout for adjustment, but I think they make one that can be adjusted in the water.
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Old 08-03-2014, 15:54   #3
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Re: from fixed to ?

I'm happy with the MaxProp on my Tayana 42(30,000#). Good sailing performance, good motoring in forward, no noticeable prop walk in reverse. Only negative is prop zincs need replacing often because the cone shape of the zinc offers little material for the bolts to keep it on the prop. This portion of the zinc is gone when there is still plenty of material on the rest of the zinc.

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Old 08-03-2014, 16:50   #4
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from fixed to ?

Seems like your not after the performance and extra maintenance, so why not just fit a shaft brake?, Maybe you have an out of balance prop and a worn cutlass?
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Old 08-03-2014, 17:15   #5
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Re: from fixed to ?

Quote:
Originally Posted by Tayana42 View Post
I'm happy with the MaxProp on my Tayana 42(30,000#). Good sailing performance, good motoring in forward, no noticeable prop walk in reverse. Only negative is prop zincs need replacing often because the cone shape of the zinc offers little material for the bolts to keep it on the prop. This portion of the zinc is gone when there is still plenty of material on the rest of the zinc.

Sent from my LG-P769 using Tapatalk
Paint the zink around the bolts alittle. It protects the bolt hole and forced more of the cone to be used
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Old 08-03-2014, 17:20   #6
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Re: from fixed to ?

I have a older max prop And I have to haul out to adjust. The motor is getting old and not as strong as it used to be. And finding the sweet spot is hard. I wish I could just dive give it a twist and motoring to get the right RPM to speed. So every year I reset it. Hopefully this is the year.
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Old 08-03-2014, 17:45   #7
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Re: from fixed to ?

A 24" pipe wrench on the shaft will work wonders until you decide on a permanent fix. But don't forget it is there when you go to use the motor again!
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Old 08-03-2014, 18:46   #8
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Re: from fixed to ?

the pipe wrench shaft brake works, but I cringe at the thought of the curls of stainless that might come rubbing off the shaft in that case. Admission time - I have frequently made a shaft brake from a short length of 1/4" double braid. secure one end against something very solid - a frame, a floor timber, an engine bed etc... then loop (carefully) three or four times around the shaft... it just slips easily until you put a little tension on the free end... and you can gently brake the shaft easily. then tie up and voila - no marks, no fuss. make sure you put an indicator of some kind (we used a clothespin) on the starter key to remind you that there is a brake on.

of course, the real issue with any type of makeshift shaft brake like this is the SIDE LOADING that it puts on the shaft bearings, transmission coupling etc. in my case it was on a large sail trainer, and I was able to locate the rope between two steady bearings - so the transmission and stern tube were not involved... but it was still a little 'outside the box' and certainly frowned upon by any experienced engineer... but it sure made a fast downwind sail a lot quieter in the aft quarters!!

I'm considering a max prop too... but I have to win the lottery first...

good luck-

bg
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Old 08-03-2014, 19:03   #9
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Re: from fixed to ?

I had a MaxProp on my last boat and have a FlexO Fold on my current. Both work good, but the FlexoFold gets a lot better fuel mileage, is simpler, and costs less.
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Old 08-03-2014, 20:16   #10
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Re: from fixed to ?

Ive seen some set up's with alternators jack shafted off the driveshaft that really kept the batts in the guy's boat! Never had one myself tho, always wanted to make one tho!!
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Old 09-03-2014, 07:39   #11
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Re: from fixed to ?

I've never understood how people can stand to listen to the spinning shafts! And if you lock it by putting into reverse (against some manufacturers directions) why you live with the loss of speed. Folding props aren't very expensive compared to lots of other crap people buy for their boats.
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Old 09-03-2014, 08:06   #12
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Re: from fixed to ?

Keep the answers coming, I am learning something from every reply.

Shaft brake not really so good an answer, the propeller is out in the middle between the keel and a skeg. even a two blade propeller would have little protection.

I built a beauty of a shaft lock on the schooner, a wooden bridge overthe shaft flange, a rotating disk of bronze, and used golf tees as the lock pins. We sheared a lot of tees over the years, but no damage ever anywhere.

Crew actually liked the prop whine/singing. It was kind of a speedometer that you could hear more or less asleep. After several days the dead quiet would wake us up more than the whine!

Yes the cutlass bearing has a lot of wear. The prop looks very clean and balanced. The wear could be as much from the 8 plus knots shuddering as from 6 knots under power. The cutlass bearing will always be wearing out, a folding or feathering prop will require maintenance, but more or less on a routine schedule.

I was a fixed prop diehard too, but this plastic boat will really go, I just have to stop towing the bucket!

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Old 11-03-2014, 20:15   #13
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Re: from fixed to ?

We have a Hundested 24" 3-blade infinitely variable with a hand crank adjustment in the cockpit. (0 to 90 degrees) 115 HP Westerbeke 6. 2:1 reduction gear. We run 8 - 10 knots at 1200 rpm engine speed. Our boat is 36 tons in the slings. This is the smallest variable Hundested makes but there are other manufacturers that are functionally the same.

It is especially nice to be able to flatten the prop at low speed for maneuvering in the marina or for maximizing the thrust to back out of mud or sand. Also, powering into heavy surf. We open up the blades as the boat speed picks up or water is flat, seas & wind following. These variable props are not cheap but they maximize performance under sail and stretch the fuel. The benefits are greater for larger boats and probably of little use on small & light vessels.
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Old 26-04-2014, 16:12   #14
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Re: from fixed to ?

We are in the same procedure of trying to figure out which of if feathering or folding would be the best for our Prout 50 Quasar, today with two fixed 17X12.
After a lot of test reading, manufacturer consulting and asking around, the folding Flexofold or the feathering Featherstream are the two options. The problem for us is that we use both Engines when docking, alternating back and forward. With lower gear on backing, I'm afraid that the folding props bad backing capacity will give problems, so at the moment we are leaning towards the Featherstream...
but still also worrying about picking up nets etc while sailing...hmmm.
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Old 26-04-2014, 16:18   #15
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Re: from fixed to ?

We had a Maxi-prop on our old boat and while it worked fine it has a lot of prop walk. The fixed prop on the new boat wasn't an option, so we went with the autostream feathering prop. It is amazing, predictable in reverse, lots of power in forward, and the customer support was exalent. I would highly recommend one.
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