question about propeller racing in foul seas

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Maestro
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question about propeller racing in foul seas

Postby Maestro » Sat Aug 19, 2017 8:11 pm

We trailered our 28 to Green Bay (the body of water, not the city!) for a trip last week and had great weather most of the time.

One of the days, we smashed our way through 24 miles of stiff 3-4 ft waves. Throttled to 2,000 rpm which equated to about 8-9 mph in those seas. In normal conditions that rpm would give me about 14 mph.

The boat did very well, but on several occasions, the propeller rose briefly out of the water and you could hear it race. Makes angry groaning/roaring sounds. Engine rpm seemed relatively unaffected. A little tremble on the tach.

Should I find myself in this position again - is the prop racing going to destroy anything ? I certainly can't imagine its good for any part of the drivetrain but I don't see any way to avoid this when caught in a stiff chop. Reducing speed further would result in very poor steering...
Maestro
1970 28' Express
Single Chrysler 440
Mississippi River

Fastjeff
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Re: question about propeller racing in foul seas

Postby Fastjeff » Sun Aug 20, 2017 5:43 am

..."We trailered our 28 to Green Bay (the body of water, not the city!) "

Had to laugh at that since my GPS has me running up the local river on dry land! (The pointer is off about 3/4 of an inch.) Weird to see buoys located on dry land!

If the props were breaking free, either those was some really nasty waves you were running in, or the boat was trimmed (weighted) too heavy forward. I've banged through a few nasty conditions with my old 32 footer and never experienced that. Do you have trim tabs, and were they down at all?

I doubt if any permanent damage was done to the engines (assuming they didn't over speed) or the trans. The shafts didn't break (obviously) so they're probably okay as well.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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Maestro
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Re: question about propeller racing in foul seas

Postby Maestro » Sun Aug 20, 2017 8:30 am

I have tabs but they are not working at the moment so they are set fully retracted.

Waves were very steep, period very close together. I think that was part of it.
Maestro
1970 28' Express
Single Chrysler 440
Mississippi River

TinLizzy
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Re: question about propeller racing in foul seas

Postby TinLizzy » Sun Aug 20, 2017 11:45 am

I have had my twin engine 28 do this many times on Lake Superior. In my mind, it is just the nature of the beast. Having a very shallow draft, makes it easier for the props to break free in the rough stuff. Tabs are a must, but they only help so much. Just keep doing the balancing act between pounding and being able to steer effectively/make head way.
Rodney
1975 28 Express-Twin 350 Chevy's, Raw Water cooled
Portage Canal Waterway-Upper Peninsula,Lake Superior

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Maestro
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Re: question about propeller racing in foul seas

Postby Maestro » Sun Aug 20, 2017 12:51 pm

does running the tabs all the way down help keep the prop under?

My tabs have never worked but I've been tinkering with them this summer. It's been a slow process but I hope to have them running soon.
Maestro
1970 28' Express
Single Chrysler 440
Mississippi River

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Re: question about propeller racing in foul seas

Postby martindesign » Sun Aug 20, 2017 8:49 pm

Cavitation, it happens. Not ideal but at that speed and rpm won't hurt anything.
Machanic, fabricator, carpenter, plumber, electrician, designer, hotrod builder and glutton for punishment. :ugeek: current boat; 1969 Marinette 32 express bridge 440's
Catawba Oh

TinLizzy
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Re: question about propeller racing in foul seas

Postby TinLizzy » Sun Aug 20, 2017 9:19 pm

Depending on sea conditions, the tabs could help out with the prop free wheeling. But the trim tabs are so much more. I would say on a typical cruise, at 25- 30 mph, I use my tabs a couple of times every few minutes. I have 5 kids, and they are always walking back and forth, and side to side, while we are under way. I use the tabs to keep the boat as level as possible side to side, and also adjust fore and aft to account for sea conditions and to fine tune for max mph while cruising.
Rodney
1975 28 Express-Twin 350 Chevy's, Raw Water cooled
Portage Canal Waterway-Upper Peninsula,Lake Superior

jralbert
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Re: question about propeller racing in foul seas

Postby jralbert » Sun Aug 20, 2017 10:48 pm

In bad weather, passengers should be told to stay put, roaming not very safe. If you have strong/heavy/big following seas (not good), tabs should be off/retracted/up. Or at least in a neutral positon. If they are down, they will keep the nose down and when you ski down a fast moving roller, the bow is likely to dig in and you could flip end over end (also not good).

If you can manage to head into waves, a small amount of tab down can steady things. You'll be taking it slow and steady and you'll get home safely.
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD

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Re: question about propeller racing in foul seas

Postby Fastjeff » Tue Aug 22, 2017 6:58 am

Perfect answer, Joel!

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

TinLizzy
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Re: question about propeller racing in foul seas

Postby TinLizzy » Tue Aug 22, 2017 6:50 pm

I was referring to people moving about the boat while cruising, not when it is rough. I should have clarified. I don't go out with my kids if it is rough. My main point was that I use my tabs all the time.
Rodney
1975 28 Express-Twin 350 Chevy's, Raw Water cooled
Portage Canal Waterway-Upper Peninsula,Lake Superior


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