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Old 05-12-2014, 11:34 PM   #21
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Really interesting constructive helpful discussion.
Slight hijack, some 4cyl 80hp Ford Lehmans were raw water cooled.
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Old 05-17-2014, 04:55 PM   #22
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Well the results are in: 1900 is Wide Open Throttle

On Thursday I started her right up and ran the figures. She ran nicely for, oh, a half hour or so. No overheating: infrared heat gun showed 95 to 120 degrees, depending where I shot.

But Friday was awful. Nothing would start her. Nothing I tried, and then the mechanic came over and gave it a shot. Finally he went upstairs to talk with the boss who asked the question "has anyone put any fuel in her?"

DUH! She ran for 1/2 hour just with the fuel in her lines and apparently just about the time I shut her down the fuel ran out. Gosh, I felt so blonde!

Anyway, a gallon of diesel, then bleed the engine and she started up like a champ. Same figures -- we are not running her under load (just in neutral at present) and 1900 sounds okay but at 825 or so she purrs.

The figures from vicprop show:
Propeller Size
Number of blades Diameter (inches) Pitch (inches)
3 Blade 16.4 X 11.2

Mechanic suggests 14 x 10 or 16x8.
Anyway, I've got the 16x16LH and that's a common prop (read: cheap to buy, impossible almost to sell) whereas the 16x8 or 14x10's are not inexpensive. He said the best he could come up with was $500. Ouch.

But it's got to be done. I'm going to give it a shot for finding something at a better price. Any ideas of places to check? Used is fine. 3-blade, left hand is perfect.

Thank you for all the advice. She (the Volvo) is a gem... she purrs. With the hatch down and the step closed I can hear conversation and the VHF radio too. I'm excited -- it's nice to be so close to the end of this swap.

I've got a diesel. And my cheeks hurt from smiling so much. Crest toothpaste should give me a retainer for all the grinning I've done!

Oh, and more good news: The shrimp boat next to me is having a fuel truck arrive Monday morning and he's reserved 50 gallons for me. At his price. How cool is that?!?

Life is wonderful afloat!
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Old 05-17-2014, 05:08 PM   #23
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Maybe give Sailors Exchange in St. Augustine a call. We were in there this morning and they had a pile of used props. You might have to get it cleaned up but you never know.

https://www.sailors-exchange.com/
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Old 05-17-2014, 05:14 PM   #24
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Quote:
Originally Posted by Larry M View Post
Maybe give Sailors Exchange in St. Augustine a call. We were in there this morning and they had a pile of used props. You might have to get it cleaned up but you never know.

https://www.sailors-exchange.com/
Thanks Larry. Is Sinclaire still there? It's been a while since I was in... (it's a good candy store -- the dock lines were a good price but I didn't need any at the time)
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Old 05-17-2014, 11:08 PM   #25
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Janice- Even with that big prop, if you run around at 1400rpm or below the engine will be happy. If that big old chunk of iron is not making black smoke, it's not overloaded. Love that big old iron...
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Old 05-18-2014, 01:31 AM   #26
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Call vicprop. They have a huge stock of used props that they will repitch for you. They did mine for my repower.
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Old 05-18-2014, 06:44 AM   #27
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Well the results are in: 1900 is Wide Open Throttle

Does the boat go fast enough at 1700 or below with no black smoke ?

IF so stick with what you have, and paint a red line at 1700.

My guess is even 1700 will be too much wake , too fast for much economy.
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Old 05-18-2014, 05:00 PM   #28
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Thank you. I've got a list of consignment shops and tomorrow will start calling them. One was found (thanks Steve) for $230, a 14x10 (1" shaft versus my 1.25" tapered) ... That's a great price, if it will work. The guy here will call on that one and any others I can find.

She runs great though -- ran her for a few today before the fuel ran out. I'm smart now. As she'd run for about 15 minutes I called it a day. Tomorrow I'll bleed the system and start the motor again.

And tomorrow I'll fill my port tank. The shrimp boat next to me has ordered 1550 gallons, with 50 designated for me. At his price, that was very nice of him. His boat is steel and yesterday he had a welder up on the bow -- smelled like "home" (when we had our steel 40'er)

I guess I'm weird, but I do own two boats (Seaweed and Algae) so obviously there are some sanity issues. I'm happy though -- and as long as no one appears with a nice jacket with extra long sleeves so I can hug myself, it's all good!
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Old 05-19-2014, 05:16 PM   #29
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Quote:
Originally Posted by Larry M View Post
Maybe give Sailors Exchange in St. Augustine a call. We were in there this morning and they had a pile of used props. You might have to get it cleaned up but you never know.

https://www.sailors-exchange.com/
I've been on the phone with Bill who works at Sailor's Exchange. There is a 1.125" shaft, 14x10 LH there for just $95. Wonderful price. At this point we don't know if the propeller is good (do you know how to test one?)

Side Note: Sinclair sold the business to Clayton Hansen (who has/had a repair shop nearby) ... and Bill works there.

To test one, apparently you're supposed to hit it with a piece of metal and if it rings, all's well?? I've heard it's called "greening" but anyway, finding out if this one is a-okay is the next step.

$95, plus shipping of course. But thus far, this one is closest. 1.125 is close enough to 1.25 (what I have) so it will work aboard Seaweed. IF it's a good prop.

That's the status as of today 19 May 2014.
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Old 05-19-2014, 05:27 PM   #30
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A 1.125" taper bore prop won't fit on a 1.250" tapered shaft. Prop will need to be bored to 1.250 and keyway broached. Well equipped prop shops can do this with a lathe and broach/bushing.
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Old 05-19-2014, 06:02 PM   #31
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Janice- I ran your numbers on the Boatdiesel calc: 20'wll, 7000lb, 15hp@ 2200rpm, full displacement, 1.9:1 gear, 3b prop. Came up with 15" dia, 10.4" pitch.

I think you would do ok with 15x10, 16x10, 15x11, even 16x11 or 15x12. Look for 3b 1.250"bore. Not sure of your gear, you mention left hand, and if I remember the old Volvos there is a preferred direction of rotation.

I would not go down to 14" dia. Gettin pretty small there.
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Old 05-19-2014, 10:25 PM   #32
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Ski in NC

14" dia = small?

Remember the 15hp part?
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Old 05-19-2014, 10:58 PM   #33
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Quote:
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Ski in NC

14" dia = small?

Remember the 15hp part?
Yep, but it's a 2200rpm engine with 2:1. Need some diameter to push on the water. 14 will push it, but slip will be high especially at lower cruise rpm. 15hp is small, yet the boat is 7000lb. This is a little out of my element, I usually deal with hundred-odd hp. Not 100% on this one.
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Old 05-20-2014, 07:34 AM   #34
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At this point we don't know if the propeller is good (do you know how to test one?)

The only way to check a prop is for a prop shop to put on a bench and check the blades with a pitch gauge .

Usually hunk of wood with the proper shape that fits the pitch, yes they usually have dozens.


AS a simple rule of thumb at 1000RPM shaft speed an inch of pitch is one K thru a non slip material.

So at 1000rom a 10 inch pitch would give 10K if the water were mahogany.

With 50% slip the 10K becomes 5K about right for this size boat.

IF the boat is lighter , slimmer and with a smooth bottom the slip might only be 40% , so closer to 6K might be observes underway.

Tied to a dock , at zero speed the engine will overload if the prop has enough blade area.
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Old 05-20-2014, 10:09 AM   #35
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Ski and FF,
Good points.
I wondered for years why Willard didn't put a 3-1 gear on the Perkins and a 20-21" prop. There's plenty of room. Don't know any repowered Willard 30 that has a bigger prop either. If I haden't kept my 2.57-1 BW gear I probably would have done it though.

But I think I understand the prop issue better now. Too much pitch and you get more slippage as the water tumbles out and around the blade tips. Thrust is lost. Too much diameter = too much blade area (unless you have a very unusual prop). At some point of increasing the dia most of the power will be eaten up just turning the blades through the water and all that blade area and nice low pitch won't have the power to push much water.

A square prop (same pitch & dia) will have too much slippage for a slow boat like ours. A prop w half as much pitch as the dia takes too much power to turn the prop and all that blade area so it produces less thrust. Seems to me I read somewhere that a prop w 3/4 as much pitch as dia has the best balance of tip losses and blade area drag so the most efficient prop lies in this pitch/dia relationship. A 20" prop w a 15" pitch, a 16" wa 12" pitch .. 24 X 18 ect. This is not to say that a 24 X 12 prop is unusable but it's less efficient.

Also a very low pitched prop would probably have more thrust at WOT and zero speed. Best for giving that 80' yacht a tow back home. With a little more pitch it would probably be best for top speed on a trawler. And w more pitch yet it would be optimized for cruise at 60% load and more yet best for cruise w a 40% load ect. The thrust cruve is steeper for low pitch and flatter for higher pitch. That's why you can put an 8hp OB on any boat and go wide open throttle. The prop has lots of slip at all speeds and therefore is very flexible.

So I think the ideal trawler prop is about half way between a square prop and on w 1/2 as much pitch as dia. People tend to feel a larger prop will have more thrust so tend to lean in that direction. So many trawlers have a little more dia and less pitch than would be optimum.
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Old 05-20-2014, 05:27 PM   #36
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Quote:
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Call vicprop. They have a huge stock of used props that they will repitch for you. They did mine for my repower.
You know Northern Spy, that's a marvelous idea. I've taken it.

Of course their computers are down today -- it's a bit hectic there I'd imagine.

But yes, they provide the calculator and if the price is close, that's what I'll go for. Used are all over the place, and the quality at least from the pictures, it would cost $$$ to recondition.

The estimate from a shop down by Tampa, with re-boring from 1.125 to 1.25 was $200 - $250. Plus shipping every which way, the cost of used... well, unless VicProp can come up with a used propeller (I'd trust them), well, I'll be dropping $500 for a new one.

Painful, but this is a one time outlay so...
I've seen a couple of online buys (here at the mechanic's) and they were ugly. It's put a bit of fear in this purchase -- a real prop company's used offering would be trustworthy. Otherwise, well, not so much.

What say the experts? This is new territory for me......
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Old 05-21-2014, 06:34 AM   #37
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I wondered for years why Willard didn't put a 3-1 gear on the Perkins and a 20-21" prop.

Probably to keep the engine from under loading.Keep down noise and have a longer service life.

Far lower piston miles.

The HP available changes with RPM, so operating at 3000RPM for cruise rather than sat 1500 will place the engine in a far more lightly loaded regime.

DIESEL Engines like to be well loaded and a boat that will cruise at minor HP needs to be geared to obtain a good load at cruise RPM.

IF you towed 1/2 mile of net probably 6-1 would make sense..
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Old 05-21-2014, 09:28 AM   #38
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Fred,
Didn't have anything to do w overpropping or engine loading.

I assumed propping correctly to rated rpm whatever the prop size or gear ratio. All the rest I've said so many times I'm not going to repeat it.
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Old 05-21-2014, 10:40 AM   #39
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The engine loading does have consideration too. I know in neutral 1910 is WOT, but the "sweet spot" (noise and vibration) is 850ish. But that's in neutral so today she leaves the dock for a test run with the newly cleaned manifold. A spin will be nice.

I've got to bleed the system and reattach the tank. Was running from a 1/2 gallon jug of fuel versus the tank. I filled 'er up Monday morning at 3.39 (shrimp boat price) so that was lovely. $125 is silly, isn't it? And that (provided Bob is right) will give me a range of 700 miles: 500 practical. We shall see.

Life is great afloat. And I'm happy. The shrimper had me blocked in (big boat) but now I see river and want to be there.

Thanks to all for hand-holding and advice. I've learned a bit and am hoping VicProp can fix me up.
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Old 05-21-2014, 10:48 AM   #40
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Janice, if boat runs nice at 850 and engine does not smoke, I don't see any harm running it there with existing big prop.

Also, if engine only goes up to 1910 no load and makes 1900 at full load, that sure does not sound overloaded. Double check full power numbers with your new tach.

Searching for a better prop might be a challenge. 15x10 or so is too big for skiboats, too small for most larger powerboats. Uncommon size.

But it is worth it to check prop shop prop piles. All shops keep old wheels around, and rarely advertise. When I needed a prop, I planned a car round trip to visit several prop shops in a 100mi radius. One shop had a nice one exactly what I was looking for, at about 1/4 the price of new. Put it on and rpm/speed numbers were magically dead on.

Enjoy the run and let us know how it goes!!
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