F25 Bilge and Limber holes

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drudodson
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Joined: Sun Apr 26, 2020 11:31 am

F25 Bilge and Limber holes

Post by drudodson »

So I've read the threads I could find on the bilge in an F25, lot of good info on bilge pumps and such. I've got my floor open and have scraped out several pounds (!) of caked on oil and grease from under the cabin sole - 40+ years worth, pretty sure I'm the first owner to open the floor except for small bilge pump hatch. Will get a thorough degreasing and cleaning. Here's my question: I don't understand why the bilge is open bow to stern. Why wouldn't I just block the limber hole between the engine bilge and the cabin bilge? And leave the forward bilge pump in just in case? Keeping engine bilge oil and crud out from under the cabin sole? What am I missing?
Lake Ouachita, Hot Springs National Park, Arkansas
F-251 Hardtop 1973 with LM 318 Chrysler (reminds me of my '71 Challenger!)

"We are all in the same boat in a stormy sea, and we owe each other a terrible loyalty." G. K. Chesterton
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captainmaniac
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Re: F25 Bilge and Limber holes

Post by captainmaniac »

It's about more than just keeping engine crud out of the forward bilge. The limber holes are there to let water that may accumulate int he bilge flow fore and aft. Not sure about the F25, but a lot of the F boats sit 'bow down', so any water that finds its way in, even if from a rudder post packing gland, will try to flow to the bow. The limber holes let that happen and get it pumped out. If you are out for a run and on plane you will be bow high - the limber holes let the any bilge water run to the transom and be pumped out by the aft pump.

If something really bad were to happen and the boat was taking on a lot of water, as long the boat stays relatively level, the limber holes will let water run both fore and aft so both pumps can work on getting it out.

If you plug the holes you could end up carrying around a bunch of water that just doesn't make it to the pumps.

Better to get the crud cleaned out, and figure out and fix any engine leaks that are causing it to be there.
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Paul - SW Ontario
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Re: F25 Bilge and Limber holes

Post by Paul - SW Ontario »

drudodson wrote: Mon May 18, 2020 8:46 am So I've read the threads I could find on the bilge in an F25, lot of good info on bilge pumps and such. I've got my floor open and have scraped out several pounds (!) of caked on oil and grease from under the cabin sole - 40+ years worth, pretty sure I'm the first owner to open the floor except for small bilge pump hatch. Will get a thorough degreasing and cleaning. Here's my question: I don't understand why the bilge is open bow to stern. Why wouldn't I just block the limber hole between the engine bilge and the cabin bilge? And leave the forward bilge pump in just in case? Keeping engine bilge oil and crud out from under the cabin sole? What am I missing?
You may know, but may not...if your (I assume) 1973 225hp Chrysler 318 is original, it likely has the factory style rope rear main seal. Although those seals are quite reliable, decades of hard work wears away the oil diverting crop etchings on the surface of the crank beneath the seal causing oil to creap into your belhousing, past the inspection cover, then to the bilge.
If you are chasing a mystery oil leak, that could well be the culprit.
1973 Trojan F25.5 - SW, ON.
2012 Triple Axle trailer
1978 C&C Mega 30' Sailboat
2014 Triple Axle trailer
2016 Highfield CL290 BL RIB
2017 20hp Suzuki 4 stroke
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drudodson
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Joined: Sun Apr 26, 2020 11:31 am

Re: F25 Bilge and Limber holes

Post by drudodson »

excellent information you two, thanks! Main motivation is getting rid of bilge-y smell in cabin. Which is from the old oil not from the water. Once I get it cleaned up I can start tracking down oil drip/leak. I don't actually think the leak is too bad (hoping), as I'm sure this is years of accumulation. I know the last two owners and no one's been under there for at least 5 years, and third previous owner was meticulous but sick the last several years. Planning on a steam cleaning to degrease, then a biodegradable scrub, put in some oil absorbing booms, and new bilge pump in engine bay.
Lake Ouachita, Hot Springs National Park, Arkansas
F-251 Hardtop 1973 with LM 318 Chrysler (reminds me of my '71 Challenger!)

"We are all in the same boat in a stormy sea, and we owe each other a terrible loyalty." G. K. Chesterton
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