Rotten Keelbeam?

Discussion in 'Wooden Boat Building and Restoration' started by Padmack, Jul 5, 2016.

  1. Padmack
    Joined: Apr 2016
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    Padmack Junior Member

    Hi

    This is my first boat - Starley Sea Nymph.

    On my first launch t took on water - slowly but surely - and after roughly 12 hours in water cockpit was about 1/5 flooded. Noticed a small amount of water inside the cabin also. Bung was firmly installed. There is some kind of concrete poured into keel for ballast so making a good visual is impossible at the moment. When I recovered the boat onto the trailer noticed water dripping from full length of keel not just where dripping would occur once out of water. There is a roughtly 2 inch beam from stem to stern and a steel strip on this fixed with screws. The wood is soft and spongey indicating rot and part of the strip 'pinged' out when I was tying the boat down - the screw gave way - the wood was saturated. My question is - is this fixable? The hull is one skin fibreglass and sound so this must be the joining between the two parts or where the screws hold the beam in place?

    Is this a known issue with sea nymphs? I cant find out online as these are rare enough boats to google!

    Any thoughts either general to this kind of repair or specific to this knid of boat welcome!
     

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  2. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    I'd hazard a guess that the fibreglass under the steel strip may have been ground through at some point, or the screws have let water in. The best solution may be to dig out the timber core, replace it and reglass. Best if you can minimise any screws through into the timber or fully epoxy the holes the screws go into. If you are very lucky you can lift the steel strip and pull all the screws out at the same time. This will allow you to poke around at the timber core of the stem and inner keel. If it is really rotten it will need replacing, however if rot is only around the screw holes these can be cored out locally and replugged and locally reglassed.

    If the boat has been kept on a mooring the screw holes will have let water through. Ironically I'm just restoring a small fishing dinghy with a variation of this type of problem - water ingress from screws through the transom...;)

    Why does it have concrete ballast? This is slightly unusual unless it is to correct too much aft weight affecting trim. In which case moving the battery and fuel tank and any other weighty item like anchor and chain forward or further foward might help. Certainly does not help internal access to the keel core....
     
  3. Padmack
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    Padmack Junior Member

    Thanks SukiSolo

    That certainly gives me fuel for thought regarding the repair. I was considering filling the cockpit (not fully) with water on the trailer to see where it seeps out as this would be a better controlled environment than floating the boat and waiting for it to sink.

    Regarding the concrete - I was inclined to believe it was to provide weight and thus stability for fishing at sea as I know the previous 2 owners used it thus although I dont know how long its there. Your suggestion it might have been to trim the weight is plausible - part of the transom fiberglass was crudely cut away to make the engine well (the outboard has a well inboard of the transom) bigger - in my opinion - to allow a MUCH bigger engine than my Yamaha 5hp. Thinking about it now that could be why the concrete was used...

    Do you think, therfore, that it would be a good idea to remove that concrete given the course of action is likely to be a fairly hefty job carried out on the external keel? Its not like the extra weight added by the concrete is needed now anyway...
     
  4. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    I'd definitely try removing the concrete. A 5Hp is pretty small, not sure how long but she's probably rated for 25/30, certainly go well enough with a 15/20!
    But you'll plod around fine with a 5 and at least you can take it home and lift it off and flush salt water out easily. The transom cut out may be to fit a different length shaft of outboard. Done it myself on a Dell Quay Dory to get a short shaft to fit. The steering system can be a bit more of a problem if not tiller, but your 5Hp will be.

    All you can really do is check the trim of the boat once she is floated in normal load condition. Make sure she is level with no undue bow or stern down attitude. Under power she should easily reach displacement speed and remain fairly level. If she tries to push her bow up a bit, just back the throttle off a small ammount. She won't plane with a 5Hp so no point trying, just get a smooth and economic ride.

    Yes you can put water in and find the 'holes'. Sometimes adding a food dye - red or blue helps to locate the true hole. But you may in fact be replacing an inside keel and part stem not from the outside. This is easier with maximum access and with that foredeck it will be a bit tight. The outer keel, the steel part will need to be removed but you can keep the rest of the glass layup.


    Often the rotten wood only needs to be replaced and bonded in with epoxy and fillers. If you use some microballoons and other fillers such as microfibres and glass fibres you can bed the replacement in pretty easily. Just make sure everything inside is really dry - epoxy will NOT stick to wet timber. A good abrasion to the glass surfaces will ensure a bond, no flaky paint or waxy gelcoat, a clean abraded glass surface - 60 or 80 grit will give you that. You should be able to get a good tight timber fit. Use dowels, notch or anything to locate itht and that will hold it in position for a tight joint. Clamp with weights if you want if needed.
     
  5. Padmack
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    Padmack Junior Member

    I managed to take a few photos of the keel in more detail. Im still convinved my best bet is to get a estimate on repairs at a yard as I think im comfort zone here where it comes to hull repairs.

    You can see in the pics the way the steel band has pulled away with the self-tap screws. Overall the wood seems to have shrivelled/withered and you can see daylight between it and the band in one of the pics. Also the pic with the roller seems to me to have a bit of wander from the pressure? Maybe its a visual trick...
     

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  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It depends on how the boat is built, but I don't think that's a "keel" proper, but in fact a keel "batten", which is an external piece that "caps" the seam of the garboard planks and in some case forms the outer portions of the rabbet. Since your boat is 'glass, it's possible it ties to two hull shell halves together, but I doubt it. It's probably the hull shell is one piece or if it is two pieces, was bonded together making it one piece.

    The metal strip is a "guard" and it's sacrificial in nature. It's designed to be easily removed or in the event of an impact, it'll pull the usually short fasteners, so it saves the hull, keel or batten from major damage.

    I'm betting this is simply a keel shoe (hull guard, rub strip, there's lots of names for these) intended to protect the 'glass portion of the hull from dings. Without access from the inside (concrete), the repair is much more difficult, assuming there's a reciprocal piece on the inside of the boat. Most often, the concrete has to come out, but in this case, I'd try to remove the batten and rub strip first, just to see if there's any interconnection with elements inside the boat. With some luck, there'll be just a few screws, which can be hacked off and the batten freed from the hull shell.

    The first thing to do is grind away the paint on the hull at the hull to keel batten interface, so you can pry it off, find fasteners and slide a hacksaw in there, to cut fasteners when necessary. Next is to jack the boat up, supporting her on her garboard planks or possibly a bilge stringer, if you can see them, not on the keel batten, so it can be removed. Next, you try to pry down the keel batten. The soft area will just peel right out, but some areas will still fight you, so slide a hacksaw blade along until you hit a fastener, then cut it off, wedging the batten down as you go. The hull needs to be pretty well supported during this, as you're going to be working under it. Once you've removed the batten, clean the contact face of the hull. If it's 'glass, you're in luck and all you have to do is shape another batten and bond it on. If there's a wooden piece between the hull halves, well you have bigger issues and the concrete has to come out.

    Instead of trying to do this all at once, just remove a 12" or so section of the worst part of the keel batten. This will tell you if there's a solid 'glass hull, some internal structure, additional wooden pieces, etc. Just hack out a healthy section of batten, clean the area good and have a look. With luck (this is my bet) you'll find a solid 'glass hull, with an occasional screw holding the batten to the hull, but no internal keel or centerline seam pieces.
     
  7. Padmack
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    Padmack Junior Member

    Find

    Just by way of an update on the situation whilst scuttling about under the boat the other day and found what I think is the remains of a fishfinder transducer. I know this boat was once fitted out with a radio antenna but there is little evidence of one of these having been installed through the hull (see previous reference to concrete in bilge.)

    The unit seems pretty well attached with the fillet seal more or less intact. My concern given this thread issue is that it is a liability for water ingress given I cant access the bilge area above it. Can water seep through these things? Is that centre circle area liable to let water around it?
     

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  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Is it a ground plate for a two-way radio perhaps ? In any case you could fill any possible entry points for water with a fillet of epoxy filler, after getting back to a solid substrate.
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    When in question, just hack it off, seal it up and start over. That does look like a sounder sensor. Ground plates are generally flatter and bigger. Given the limited access you have to the inside of the boat (and finding leaks) I'd knock that off and fill it in.
     

  10. fisherkelly
    Joined: Dec 2016
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    fisherkelly New Member

    It's doable but might take a lot of work!
     
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