Hollow Keel

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psneeld

psneeld

Guru
Joined
Oct 15, 2011
Messages
28,175
Location
USA
Vessel Name
Sold
Vessel Make
Was an Albin/PSN 40
Was grinding my bottom off due to delam/hydrolysis...saw a dark spot along the bottom of the keel amidships (looked wet too). So I ground a half inch into the corner of the bottom of the keel and ...wow... a stream of water like a garden hose started...

Then I ground some more and double that came out for at least 15-20 minutes. I'm guessing somewhere 50-100 gallons came out.

With a flashlight and a stick...it looks to just be a hollow cavity..but the water came from somewhare...any ideas???
*
Scott Neeld
Albin 40 Trawler
 
Scott - Can you tell if the water is salty or fresh? Any oil in it? Above the keel, or at the engine room floor, is there any sign of water? Consider, if all turns out ok, adding a drain plug to the area you opened. If you store her on land in the cold climates, that drains the keel. Common item on sailboats, don't know about powered vessels. Other possiblilty if it is salty -the seal where your shaft penetrates the hull. Is that in the keel, or above?

-- Edited by Old Stone on Sunday 19th of February 2012 11:34:59 AM
 
Many Taiwanese-built boats were constructed with hollow keels - a number of owners have accessed them from the bilge and filled them with cement for added ballast.
 
You may want to add food coloring to a 5 Gallon bucket of water. Slowing pour in engine space bilge with some one watching outside. If nothing comes out, move aft and try pouring in Lazerette. You are trying to isolate the entry point. If nothing comes out the bottom, now you know it either entered around rudder or shaft holes. Next way would be the constant water pressure on the outside of the hull working its way in thru a crack or around a thru hull under the water line. Polyester resin is NOT a water block. In time water wicks thru and into it. If you can borrow a moisture meter do the whole hull noting the readings with a marker on the hull. Never move the meter pad over the hull. Place it on, note the reading. Lift it up and place on next spot. Sliding it along the surface will ruin the meters sencing pad. Before you go back in reread and mark down new value.
 
Pitting of the (metal, even SS) tube around the prop shaft,*if it passes through the hollow keel,*is a possibility, or*probablity.

*If you have a wet bilge maybe seeping through holes, over the keel, drilled for bilge pump attachment or the like.
Good luck, please keep us posted as to what you find.
Steve W


-- Edited by Steve on Sunday 19th of February 2012 02:40:42 PM
 
Ron T wrote:
You may want to add food coloring to a 5 Gallon bucket of water. Slowing pour in engine space bilge with some one watching outside. If nothing comes out, move aft and try pouring in Lazerette. You are trying to isolate the entry point. If nothing comes out the bottom, now you know it either entered around rudder or shaft holes. Next way would be the constant water pressure on the outside of the hull working its way in thru a crack or around a thru hull under the water line. Polyester resin is NOT a water block. In time water wicks thru and into it. If you can borrow a moisture meter do the whole hull noting the readings with a marker on the hull. Never move the meter pad over the hull. Place it on, note the reading. Lift it up and place on next spot. Sliding it along the surface will ruin the meters sencing pad. Before you go back in reread and mark down new value.
Click to expand...
*Thanks everyone...all things I've thought of.* As for a moisture meter...way past that one...some other posts of mine have already described I've ground off all the paint, gel coat and at least the layer of mat between the gel and roving...yesterday I chiseled a 4x4 foot suare as far down as six layers of roving/mat.* Have lots of epoxy work as soon as the weather warms!

Just not sure what to do with the hollow keel...thought about 2 part foam but a couple manufacturers say it eventually absorbs a little and will pull away from the side...well what good is that?* :)
 
WESTERLY has a hollow keel, although it was filled with a type of foam during construction in 1973.* The foam has contracted, so there is space around the foam.* In 1998 (after purchase), the boat was hauled and the shaft removed.* In order to make this happen, the skeg/rudder support had to be removed.* As soon as the bolts holding the skeg were backed off, out came the water.

We let it drain/dry for a couple of months (actually, we made a few holes in the keel to make sure we got it all out).* When it came time to remount the skeg, made sure that the skeg and bolts were well bedded.* During the time on the hard, a deck fill fitting was installed in the top of the keel located just forward of the intermediate bearing in the main cabin bilge.* I check for water once a year.* It's been dry ever since.
 
psneeld wrote:So I ground a half inch into the corner of the bottom of the keel and ...wow... a stream of water like a garden hose started...
Click to expand...
A hollow keel or partially hollow keel is pretty typical of boats of this type.* Grand Banks boats have hollow-ish keels, for example.* Most of them have a means of pulling the water out of the keel-- a stub pipe coming up through the floor of the engine room is the most typical thing used on GBs.* Some GB owners have installed drains in the keel to use when the boat is on the hard.* This is particulaly critical for boats that live in places where the winters are really cold and boats are stored on land.* Water in the keel can freeze, expand, and crack the keel open.

The water can get in any number of ways.* Something as insignificant as the screws holding an "impact" strip of stainless or bronze strapping to the stem of the boat that runs from above the waterline to below it can admit water through the screw holes if they penetrate all the way through the hull and the impact strip is not properly bedded or if the bedding is no longer doing its job.

While it's said by the experts on the GB forum that water in the keel of a boat with a solid fiberglass bottom, like a GB, is not structurally detrimental in itself, it can over time add a lot of weight to the boat.
 
My brother in law had a 36' Grand Mariner, the B.C. version of the Albins. It's been gone from his hands for many a moon. However, he had a similar dilemma, water comeing into the bilge from around the shaft log, not the stuffing box.
The shaft liner tube from cutless bearing to the shaft log had corroded through allowing water into the keel.
It was ground out and replaced at the cost of a lot of work and $$.
Don't know if he really had to do it but the decision was , do it.

Hopefully this is not your problem. You might try pressure testing the tube to see if you have a similar problem.
 
On a side note, I am aware of a*situation where adding keel length to an Al hulled*vessel was required*to deal with a cockpit extension. The naval architect designed it so that an Al compatible antifreeze solution could be added to the hollow keel extension to improve stability versus just airspace. About 150 gallons of solution was added. Weight down low isn't all bad and in many case is intended.
 
I think I'll add an interior drain pipe so I can monitor what the heck is going on.

The thought of adding something to keep water out is tempting and if heavy will add some stability (not sure I need/want that much more)...but till I know how fast it's coming in..hard to get worried...

Yeah...I don't even want to contemplate a shaft log replacement...one yard I spoke to said they would never do another one!
 
One of the things that came up in our pre-purchase survey was a poor repair job on the keel as a result of the previous owner contacting a reef in the Canadian Gulf Islands. Looks like they put a band aid on it to keep going on their cruise. After the first season, we pulled it for painting and cutlas bearing replacement. The area of the patch continued to weep water after several days. We ground out what appeared to be Bondo under a thin layer of glass, then vacuum bagged the area and let a shop vac run for about a week straight until no water would come out. Probably no more than a couple gallons total. Ground it down a little bit more then had a pro come in and patch it. No problems since, but it's kinda hard to tell.
 
charles wrote:
Scott,
No speculation here is what I did.
Found a small amt of water, it could have come from either a screw that was holding a bilge pump to the eng room sump floor or a very small crack in the keel, very small as only about gallon of water would come out on haul out. Crack was at the back end of the keel.
Actually not a huge job to fix, though it sounds so:
I cut a hole in the side of the keel abt one foot high by 2.5 long. Made a beam of two 2x4's and wrapped in fiberglass. Placed this inside the keel and glassed it in. This was at the extreme back end of the keel where it sits on the rails when being hauled out. The repair made this area really strong. Used the peice of glass that I cut out to close up the hole, put a couple of peices of wood inside the keel to hold the cut out in place until the glass hardened. Once sanded and painted, could not tell the job was ever done. Pics and description of the repair was placed in the repair binder for the boat.
I, of course , fixed the screw hole in the sump with a dab of glass.
At the back of the eng room, this is a P/H boat, I cut a round hole in the floor and installed a plastic screw down inspection plate, abt 6-8 inches in diameter for access later if needed. Never needed it!
I did not put in concrete nor foam nor anything else, did think it through, but quickly disabused myself of such due to the difficulty of any future problems, as this would make repairs much more difficult.
Click to expand...
*Not sure what the advantage of your wooden beam is....if it din't seal up the whole hollow keel or cover a known leak...what was your reasoning?
 
Kept the boat...problem was my hollow head...:D

Actually just drained the keel...and went cruising.

September for my week yard period...will be checking all underwater parts closely. If I see that more needs to be done, will drill into the keel and see what I have now.

Good news, no blisters or further hydrolysis for the last 4 years....and 10,000 miles plus Superstore Sandy under her belt...:thumb:

If I get water out of the keel, at that point I will roll the dice and see whether a major shaft log repair is going to hapoen, or just let her ride and see if she lasts the 15 more years I need her as a home.

And that is the issue...I really don't want to do that project and I don't want to live on the hard long enough to git'er done.
 
hollow keel

We just got 60 gallons of oily nasty water out of our keel (GB49), on glass blasting of the bottom, and discovery of a bandaid glass repair of the aft keel after an apparent past grounding. Seepage from the keel lead to a few holes being drilled, and then a flood. Why the hell do they build a hollow keel?? but i digress. My proposed solution is to pump a quantity of epoxy leavened with micro-balloons or glass flour, and filling the void completely. Any experience with this? Apart from concrete?
 
toadifer said:
We just got 60 gallons of oily nasty water out of our keel (GB49), on glass blasting of the bottom, and discovery of a bandaid glass repair of the aft keel after an apparent past grounding. Seepage from the keel lead to a few holes being drilled, and then a flood. Why the hell do they build a hollow keel?? but i digress. My proposed solution is to pump a quantity of epoxy leavened with micro-balloons or glass flour, and filling the void completely. Any experience with this? Apart from concrete?
Click to expand...
Your keel contained 60gal of water so you want to pump in 60gal of epoxy???
Beyond the price, the heat that would result of that amount of epoxy setting would melt the whole earth and create a new star in our solar system [emoji846]

L
 
55 gal is $3400. 5:1 mix of slow hardener catalyst should limit heat and cost. micro balloons will add volume, so maybe only 25-30 gallons of resin needed
I am pretty sure we will be way south of temperatures associated with white dwarves. Or we just go with concrete...
 
Last edited:
That amount of epoxy even with slow hardner will experience thermal runaway. And if it does how would you stop the process in time to save the hull? Not the way I would go with it. I would repair the questionable areas and then seal it up. After it is sealed up maybe put in an access hole to examine it periodically and pump out any water that gets in. Or do something like concrete, but that also has some inherent problems.
 
I would consider a closed cell, 2-part polyurethane foam. You can go with a lower density to fill the space or a higher density for weight or compressive strength, etc.

Drill some holes, mix, pour, wait for expansion, repeat until full, then cover your holes with a piece of glass Just, or thickened epoxy, or however you prefer. Just don't over fill or the pressure can break things Have some holes it can vent out of, just in case.

They have some 12lbs density foams that are in caulk gun style self-mixing dual tube injectors. But, for a significant volume, I'd just mix and pour and save the money on the injector gun.
 
Or....often on these designs the water can get in multiple ways.


My boat had the same...keel full of water. Probably was that way for many years.


The best solution I have heard is put a screw /plug hole on the keel and drain whenever the boat is on the hard. Many boat through the years of fixing entry water points here and there finally become dry, some don't.


Water in there isn't really a big deal except for freezing....some boats have 'glass water tanks there.
 
psneeld said:
The best solution I have heard is put a screw /plug hole on the keel and drain whenever the boat is on the hard. Many boat through the years of fixing entry water points here and there finally become dry, some don't.
Click to expand...

That's exactly how I fixed mine. First a drain, 1/2 NPT tapped into the fiberglass, and an allen head plug (so there is no protrusion), and lots of 5200 to seal it.
It took about 4 winter haul out seasons for all the water to drain. Then I put the plug back in using muck more 5200 to seal it.
In my case the "leak" was 2 screws holding a bilge pump to the bilge were no longer sealed. I fiberglassed the whole area and secured the bilge pump in a different way so no screws went into the hull.
 
The problem with expanding urethane foam is it will absorb the water that leaks in. Another possibility is foaming epoxy, which is not water absorbing. West makes it and probably others, not cheap but a permanent fix and has few exotherm problems even in big volume. With any expanding product you want to be sure there are some overflow exits as they can exert a few psi while expanding.
 
I'm no expert in this, but to the best of my knowledge, a high density closed cell foams should end up with very little moisture inside. The structure is one of polyurethane plastic enclosed bubbles.

No foam is perfect. I think even a closed cell foam has some percentage of imperfect cells.

If a closed cellcfoam is allowed tovbecome.mechanicslly damaged, e.g. by repeated flexing, then it can degrade over time and get more water inside.

2-part foams used for floatation, for example, are susceptible to this if loaded.

But the higher density structural foams are more durable and have more polyurethane plastic and less void.

I really wouldn't expect water absorption to be a problem in a good (reasonably uniform density) 2-part foam with a reasonable density in a part of the boat where neither UV nor mechanical load nor water pressure can work against it.

They use 2-part foams to prevent water from.leakingnthrouhj cracks in concrete foundatuons and the repairs are considered permanent (but, unlike epoxy, a sealer vs strength-restoring).
 
Two part urethane foams are notorious for water absorption. As examples, dinghies using two part foam floatation will become heavier over time as the foam absorbs water; if used as an insulator for an ice box the R value decays to a fraction of its original value as it absorbs water. Neither are mechanically stressed. It isn't like a sponge, but not like a block of structural foam either. Even the structural foams (airex, klegecell, corecell, etc.) absorb some water, just a lot less. Styrofoam bead board absorbs quite a lot of water, extruded PS very little.

Wet 2-part foam inside a hollow keel probably has few consequences, but structural foam fill (impossible after the build) or foamed epoxy are no doubt better.
 
But why put foam of any sort in? I can think of no benefit and lots of challenges. If given a choice between filled with water or filled with waterlogged foam why would anyone choose waterlogged foam? The only possible benefit would be to provide buoyancy by displacing water, but you don't want or need a buoyant keel.
 
Jeff F said:
But why put foam of any sort in? I can think of no benefit and lots of challenges. If given a choice between filled with water or filled with waterlogged foam why would anyone choose waterlogged foam? The only possible benefit would be to provide buoyancy by displacing water, but you don't want or need a buoyant keel.
Click to expand...

I agree. Why do it. Just put either a drain for when it is out of the water or put in access ports and pump it dry occasionally. Once the foam is in and gets full of water it will be very difficult to get the foam out. Not a crap shoot I would be willing to take.
 
How about vacuum sealed freezer bags of sand?
 
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