Albin 27 driveline variations

[WillieC]

Reply to Bob..

I like 'free'. Any and every good prop shop will do the homework if you give them all the right info. I submitted my A25 specs to two shops and they both came up with the same prop, interestingly, one inch in pitch less than Official Per Brohall Owners Manual. Oh, and those two results matched the pink prop I had on the boat. Well, not the color...

That's not to say one can't research and do their own homework...check your math. Plenty of prop calculators on the interweb. There is also considerable discussion about cupping going on, that I know nothing about. Then, of course there are the real world applications we submit our boats to, like overloading them. I have also read of trawler folk who intentionally overprop and then never run wide open. This reduces rpm and supposedly improves mileage. At 6 knots, I hope to have all 36 horses available for the inevitable ferry encounter here in the Salish Sea. Those suckers move. It's all about t-t-timing.

[Bob Noodat]

Reply to Bob..

I like 'free'. Any and every good prop shop will do the homework if you give them all the right info. I submitted my A25 specs to two shops and they both came up with the same prop, interestingly, one inch in pitch less than Official Per Brohall Owners Manual. Oh, and those two results matched the pink prop I had on the boat. Well, not the color...

That's not to say one can't research and do their own homework...check your math. Plenty of prop calculators on the interweb. There is also considerable discussion about cupping going on, that I know nothing about. Then, of course there are the real world applications we submit our boats to, like overloading them. I have also read of trawler folk who intentionally overprop and then never run wide open. This reduces rpm and supposedly improves mileage. At 6 knots, I hope to have all 36 horses available for the inevitable ferry encounter here in the Salish Sea. Those suckers move. It's all about t-t-timing.

Now, that's a non-answer. As a college professor, I got really handy with those if I had no clue. But, that makes it difficult to palm me off with one. Simple question, the answer more than likely is one good Web article which cites sources you csn consult if you wish to know more.

[WillieC]

https://www.vicprop.com/calculator.htm

https://www.miwheel.com/inboard-propellers/prop-it-now/

There are more.

[Bob Noodat]

https://www.vicprop.com/calculator.htm

https://www.miwheel.com/inboard-propellers/prop-it-now/

There are more.

I knew I could goad him into action! Where's the more then?

[SkipD]

Extra food for thought on prop sizing (Passage Maker, Nov/Dec 2014, "In Praise of Oversizing, Big Pros of Oversizing Propellers Far Outweigh the Cons" Nigel Calder, it's also available here https://www.proboat.com/2014/07/praise-for-big-props/)

[Bob Noodat]

Extra food for thought on prop sizing (Passage Maker, Nov/Dec 2014, "In Praise of Oversizing, Big Pros of Oversizing Propellers Far Outweigh the Cons" Nigel Calder, it's also available here https://www.proboat.com/2014/07/praise-for-big-props/)

Now that is interesting. I worked on tugboats as a young man, mostly small ones, 70 feet or less. Wonderful power they have, often with surprisingly little horsepower.

There's a fantastic little tug for sale near Portland now, to be found on CList.

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Described as:
Retired US Army Steel Tug (ST-1988) - $165000 (Cathlamet)
Welded Steel Tug For Sale
Bemis Heights is a retired US Army small tug (ST-1988). Built in 1954,
at Missouri Valley Steel in Leavenworth Kansas, she is a welded steel,
model bow tug, 70 feet long, with a beam of 20 feet, draws 8 feet of water
and displaces 100 tons. She is currently configured recreational.
She was sold surplus by the US Army at Tacoma, WA in 2001, has been
moored in fresh water since that time and is in excellent condition.

ENGINE ROOM
Power is a rebuilt Detroit Diesel 16V71NA with 623 Hp @ 2300 RPM driving a bronze, 6 foot diameter,  4 blade, 60 inch pitch, propeller through a 5-1/2 inch bronze shaft through a TwinDisc 514, 4.5:1 reverse and reduction gear.

The size of that prop! So large props I get. Pitch, number of blades and sizing to match horsepower, hull size and type, and desired performance I do not yet get.

[motthediesel]

Bob,

Ah, propeller discussions -- they can go on for ever!

All those links above are great, and thanks to the folks who had posted them. For a really deep dive, you might enjoy this too:

https://www.amazon.com/Propeller-Handbo ... 0071381767

Written by Dave Gerr, informative, but understandable for the layman like me. In other words, written so "even I can understand it"

Tom

[Bob Noodat]

Thanks Tom. I shall look out for a used copy.

The little research that I did today seemed to indicate that any theoretical maths on the subject turns Greek in a hurry, but that boatbuilders, at least of large boats, put hull models in a tank and try a bunch of different props to make their final choice.

[sail149]

The only reason I'd repower is to give me more room in the ER for these old bones to squish into. I almost did repower a year ago but at the last minute cancelled because of a medical issue. I was going with the BETA 50 myself. Ben

That is so true. I was amazed when I first looked at the Lehman/Peugeot by how BIG it is. I have a lot of experience with VW diesels, and the 2.1L Peugeot block is at least 30% bigger than a VW 1.9. I've rebuilt a number of 1.6 and 1.9L VW's, and I can pick a short block up with my hands. I'm not sure Andre the Giant could do that with the Peugeot.

In fact, a marine-ized, non-turbo VW would make a nice light and compact prime mover for one of these boats. It would also be handy to be able to get any part you needed at the nearest NAPA or Autozone.

Tom

Hi , Perkins Prima motors were made with the VW engine . My dad had one in a sailboat , ran like a champ, he brought in an auto mechanic to work on every now and again ( he was in UK where auto mechanics work on diesels!) what was interesting was the raw water had a huge pump and the water coming out the exhaust was like a fire hose ! Never seamed to be a problem it was his last sail boat (37') and got a lot of motor use . Cheers Warren

[WillieC]

You’d never have any emissions trouble with the VW either. Win win.