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capnfox

Fiberglass Sander

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Jul 1 13 12:55 PM

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We have finished the install of Yanmar 10hp in Swallow (see images). I am now thinking about the prop. I believe this engine will be adequate but this boat has a two-blade prop and I am wondering if going to a three-bladed prop would give me some extra oomph or if it's not worth the trouble. Any suggestions, comments welcome.





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#1 [url]

Jul 3 13 11:21 AM

I have used a 3-blade 12' diameter prop on my B29 since 1990 when I repowered to a Yanmar 3GM30F. I've never regretted using this prop. I don't think I suffer from any measurable drag with the extra blade and the prop gives a lot of bite. I'm sure either a 2-blade or a 3-blade would work fine. What is the ratio of the transmission you are using?

Cheers,

David

Restoring a Bristol 29 in my backyard. www.bristol29.com

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capnfox

Fiberglass Sander

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#2 [url]

Jul 4 13 7:17 AM

Hi David,
Thanks as always for prompt reply. I'll find out what the transmission ratio is and come back to you. My mechanic wants to run the boat around a little with the two-bladed prop to see how the boat responds, get a baseline etc. Thanks for sharing your experience with the three-blade. I'm leaning that way, but will investigate more. The displacement of these boats is about 8,400 pounds, yes?
Steve

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capnfox

Fiberglass Sander

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#4 [url]

Jul 7 13 8:32 AM

We bought #75 from a very nice couple who had discarded the frozen A4 in the boat when they bought her and instead installed a real Rube Goldberg arrangement -- a 10-hp Tecumseh, air-cooled gas engine with a plastic jerry jug outboard fuel tank that sat in the cockpit. Basically a glorified lawnmower engine. PVC pipe for the water that cooled the air exhaust. The engine "mounts" were two hunks of West Systems epoxy glued to the hull, with the bolts screwed down into that. So we tore everything out, down to bare hull inside, and built engine beds of laminated apitong, glassed to the hull, mounted a shelf for a new stainless tank above the Yanmar, etc. etc. Was quite a project, and much more expensive than I realized. But now we have what is essentially a new engine, new installation, new tank etc. Have also installed windvane (that came with the boat), roller furling and lazy jacks for the main, had new dodger cover and sailcovers made, new teak hatchboards and a gorgeous mahogany table to replace the original (will send photos when all is in). I knew the B29 was a tank, with great lines and an easy motion, so I was willing to undertake a full restoration. I will probably put an electric windlass in over the winter, but for now the manual Lewmar is OK. Our primary cruising grounds are California's Channel Islands, which are pristine and beautiful but can also be quite rough -- and there are no fully protected anchorages, so you want a boat that can handle bad weather. Really looking forward to spending some time with the boat during the summer.
Cheers,
Steve 

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capnfox

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Aug 20 13 1:00 PM

Had our first shakedown cruise to Santa Cruz Island -- about 25 miles offshore from Santa Barbara -- and it was glorious to be back on the water in the restored Swallow. The boat handled beautifully, and the skipper's skills are coming back. I was, however, disappointed in the thrust we're getting from the 10-hp Yanmar and am definitely going ahead with the switch to a three-bladed prop. The prop shop wants measurements of the length of the rudder shaft, the gap between the leading edge of the rudder and the end of the prop shaft, and the gap between the lower edge of the hull and the prop shaft -- basically the aperture where the new prop will go. I should have taken these measurements when we were hauled out -- actually I should have overridden my mechanic and made the switch then -- but I didn't. Does anyone have these specs? Any guidance much appreciated here -- we'll be running the engine at about 2800 rpm for cruising, I think. Redline is about 3400 rpm.  As a stray thought -- I don't have the boat loaded down with gear, but I wonder if she isn't heavier than the 8400 pounds given as the displacement. Any comments on that.
All in all, I'm really happy with the restoration and the performance of #75. I just need to know I can get off a lee shore, because the winds at the Channel Islands can be fickle and fierce.
Best to everybody,
Steve Fox 

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#6 [url]

Aug 20 13 1:57 PM

Steve,

I don't understand why your prop shop would need to know those measurements. The boat will take a 12" three-blade prop, no larger. The taper on the prop shaft should be standard for any prop. You cannot fit a folding blade prop, there simply isn't room. All you need to do is replace your two-blade prop with a three-blade prop.

David

Restoring a Bristol 29 in my backyard. www.bristol29.com

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capnfox

Fiberglass Sander

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#7 [url]

Aug 27 13 12:26 PM

Hey David,

Thanks as always for your prompt response. Not sure either why the prop shop needs all that data, but I had the diver do the measurements when he took off the two-blade and the prop shop is now ordering me a three-blade. I think there's some concern on their part that because the engine is just 10-hp, a three blade still isn't going to provide a lot of oomph, but I think things will be fine. I will get more thrust and whatever that is will have to be enough. I will have to be careful about the weather, which I am already, so I don't get caught on a lee shore at the Channel Islands, but otherwise the boat will move along fine and sip fuel. You mentioned when I first asked that I would probably get about 4 knots with the 10hp and you were right. I don't really care about top speed, but I do want more thrust in a seaway than I'm getting with the two-blade. I'll let you know how things work out and thanks again -- this forum is really great.
Best,
Steve
PS -- Photo is from shakedown cruise to Santa Cruz Island -- this is Arch Rock on Anacapa Island. 


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#8 [url]

Sep 3 13 7:59 AM



Hey Steve,

One thing to remember, the B29 sails to weather so well and points so high that even reefed way down she will still make good to weather. I have sailed my boat in 35-45 kts of wind tripled reefed with a 90% jib and she still pointed very high and made very little leeway. I was able to tack to windward up a very narrow channel (the Banana River on the eastern side of Merritt Island) with the wind funneling directly down the river. There was so much wind the Coast Guard followed politely to stern in an RIB, fulling expecting me to lose the mast,run aground or blow something out. But the boat did really well. There are not many boats that could make distance to windward under those conditions.

As for the horsepower, my boat originally had a Volvo MD2B, turning a three-blade prop, less horsepower than what you have and she did remarkably well. Obviously more HP is better but I think your Yanmar will do fine and get twice the fuel economy that my 3GM30 gets - probably a pint an hour.

I like your sea hood. Where did you get it, or did you build it?

Another quick question. I see in your photo above that you have acorn nuts on the port frames? What is the story there? Are those the original aluminum frames?

Best regards,

David

Restoring a Bristol 29 in my backyard. www.bristol29.com

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