Tuesday, May 4, 2010

Propulsion System

The old propeller shaft was a little worse for wear so a new Aquamet 22 shaft was ordered to replace it. The Stern tube assembly was removed and the old cutlass bearing was pressed out and a new one installed.
I wanted a dripless coupler but could not find a stock one with the correct shaft to tube sizing so I called the folks at Fisheries Supply to see what they suggested. They gave me the number for PYI, the manufactures of dripless couplers and suggested I give them a call. PYI said "can do" and had a custom one built for me at no extra charge and sent it out within the week. The old stuffing box will be tossed in a locker and kept as a spare.

 I'm going electric for the propulsion system and needed to replace the propeller but was unsure of what pitch I should use. I emailed Michigan wheel, a popular propeller manufacturer and gave them all the specs for the vessel and drive system. They had their design team look at it and a week later they came back with the response; use a 12x10 machine pitch propeller with a 7/8" tapered bore to fit my shaft requirements.
The machine pitch style has nice big rounded blades that are ideal for vessels under fifteen knots.
I asked our local prop supplier to get one for me. What showed up was a used beat up speed prop that looked like someone had taken a hammer and a grinder to it. The only thing it was appropriate for would be a door stop! I sent it back and specified new and gave the specs provided by Michigan Wheel. They are a Michigan wheel dealer so I figured it would be an easy sale for them. They stopped by a week later to drop off some props for another vessel and told me mine was a "Bastard child" and not available and the only way I'd find it was if someone had an old one on the shelf for years they would love to get rid of ......good luck finding it.
I told him that I thought that was an odd response given that Michigan Wheel had just spec'd it out so it must be available. He shrugged his shoulders as he headed for the door "I don't know what to tell ya, we don't have it and cant get it".
As soon as he left I went online and Googled it. Two sites came up with good results, one was in Portland Oregon and one in Florida. Deep Blue Yacht Supply Inc. in Forida was more than a hundred dollars cheaper for the same prop so I gave em a call. They were very knowledgeable and said it was no problem getting the prop however it is a special order and will take six weeks to get it made and shipped. I ordered the prop and shaft from them.
The shaft arrived promptly and looks good. I would have prefered the keyway to have radius corners and the end ramped but it seems hard to teach and old marine machinist  new methods......they want to stay with what they know works dang-it! I'm sure my shaft won't be the odd one that fatigues and cracks from the non-radius corners.....and the prop wont bind on the non-ramped keyway.  Once the prop arrives we will install the shaft and lap the prop to the shaft.

Sue Nelson has been working on the design of the reduction pulleys and drive belt for the system. Sue is an Application Services Specialist with Veyance Technologies Inc. They deal with power transmission products. Sue spec'd out the appropriate components for the system and we should get them ordered next week.  We are using a belt system with two pulleys and an idler and two to one reduction.

Gary made a template out of plywood  and the motor mounts, test fit it and made a few reference marks on the hull for their placement. Once he was done I climbed aboard to make the foundations for the motor mounts. I used some five minute epoxy and glued some foam blocks to the hull under the marks. Once the epoxy had set I used various sanding tools to contour the blocks to the hull leaving the tops flat for the motor mounts to rest on. Bi-axial fiberglass and roving was laid up over the blocks leaving the tops open. Once cured the foam was pried out and the fiberglass "cup" that was left was filled with west system and west 404 high density filler. Once that was cured the top was sanded flat and bi-axial cloth was laid-up down the hull, over the top of the mount and down its side to the hull again, tying it all together. Stainless steel inserts will be fit into the base and the motor mounts threaded into the inserts making for a very strong assembly.

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