Boat renovation questions - deck foam and keel rot repair

[Cret]

Hi all

I'm shortly going to renovate my old 16' Teal, with the main jobs being to repair rot in the keel, and replace the deck which was rotten through. It had been skimmed with glassfibre previously which let water in but not out, so now I'm rectifying someone's handiwork.

Here's the horrible mess I'm facing presently:

Now after speaking to various boatyard people I understand I need to thoroughly dry the keel, then treat it with a penetrating epoxy which in theory will seep through the rotten parts of the keel wood and from what I'm told at least make it stronger than it was to begin with. Any bits which are really bad I can excavate and replace presumably?

Once that's done, I can build a new deck. I know a lot of small boats like this which are more modern than mine have bouyancy built into the decks, and since there are a number of small compartments beneath the deck (as you can see in the horror show photo above), I figured this would be an ideal space for putting some sort of foam to achieve the same thing.

I have no idea what kind of foam would be appropriate for this however so would appreciate experience advice. Obviously it needs to be something that, should water get in there, it cannot just be absorbed into the foam and weigh it down or cause rot, but my intention is that these areas will be sealed to prevent any water ingress. Ideally, something like a can of expanding foam (but impervious to water) would be ideal, but I don't know if there is such a thing that's specifically intended for marine use?

Re' the epoxy - if anyone knows of the use of this sort of thinned 'penetrating' epoxy I'd be grateful to know of recommended brands/outlets etc, and if there are particularly good ways of applying it.

I was told by one old hand for instance, that after drying the keel fully, I should remove the worst bits, then drill small bore holes into the rest of the keel at intervals, to help the resin get right down into the wood fibres to really strengthen it.

Thanks in advance for any useful information.

Jim

 

[Tranona]

Couple of observations. Not sure it is good advice to try and cure the rot with epoxy. While some of the epoxies can penetrate wood fibres, they are intended for use on sound wood. The only solution to your rotten keel problem is to rip it all out and replace it.

Regarding decks, it is not common to use foam in decks. Think you are confusing this with the common practice of using foam rather than balsa as a core to GRP to increase stiffness without adding weight. It has the advantage of not rotting like balsa if water does get in, but is more expensive. It comes in sheets and is glued to the outer laminate before laying the inner.

 

[Cret]

Thanks for the reply.

Strange about the epoxy thing as a couple of different experienced repair people suggested this and told me the penetrating type thinner epoxies are meant for this purpose.

I don't know of course so I'm not questioning what you've said, just repeating what I'd been told previously. Sounds like that might not have been best practise.

If I rip it all out, given that the boat is probably 30+ years old is there something other than timber that would be a decent and potentially lighter weight alternative?
Eg box section, or a composite sandwich of some sort?

Assuming good old wood is best, what kinds are best for this sort of purpose? I'm looking forward to the job, but not well experienced with the best materials for things like this.


Re' the foam question I guess I misunderstood as I knew that it was used for strength in composites, but also was under the impression it was also used in the way I described as well. No worries if that's not the case.
Assuming then that these compartments will not be filled, is there any merit to using them as small storage compartments, with deck pieces that lift out/hinge, or is it important on a small tub like this that the deck is one big piece for rigidity of the hull or suchlike?

Thanks for the info - it's all appreciated!

 

[Tranona]

I expect the keel is softwood. Its main purpose is to stiffen the GRP. However, water gets in and rots it. You can use softwood for replacement, but coat it in epoxy before fitting it and then use epoxy to laminate over it - it will then outlast you and the boat!

Generally speaking foam is not a good idea on boats. It has to be closed cell so that it does not absorb water - and expanding foams are not usually this type. Not sure what you mean by building a new deck, but I assume that you are talking about covering the cockpit floor once you have rebuilt the keel. Easiest way to do that, and might even be the way it was done originally - is marine ply, but epoxy coated and then laminate to the hull round the edges. You could glass it all over with epoxy and glass cloth then paint with non slip paint.

 

[Cret]

Very helpful thanks. I'd kind of expected you to suggest that hardwood should be used for the keel for maximum strength but then the stuff that's there doesn't appear to be, and that's good for me as it makes it easier to work with replacement stuff, and cheap to buy whatever is needed.

That was my concern about foam - I like the idea of using it in these little below deck compartments but it sounds like this isn't the norm so I won't try and do something that others generally aren't.

Yes, you're absolutely right about what I mean re' a new deck. Sorry I wasn't specific about it. This is more or less what the previous owner had done, but somehow they'd done it so that water was getting in beneath this, but unable to get back out, hence a nice neat appearance above deck, but carnage beneath.

That all sounds ideal and relatively easy to implement. The only thing I'm wondering about is whether it'd be useful potentially to either:

1) Have some 'hatches' incorporated in the deck in places, to make use of the spaces beneath for stowing things, or
2) To leave existing drainage holes running through each compartment so water can get in and back out (rain water) again, or to entirely seal off the area under the deck so water can neither get in nor out.

Either of these a particularly good or bad idea?

 

[Tranona]

Can't see whether the cockpit is self draining overboard. If it is, it has to be watertight and above the waterline. If it is not then you need some arrangement for a bilge pump to clear water. Would not have any access hatches as they can leak and you are back where you started.

 

[nickd]

I second Tranona, dont use foam. If you work on the basis that whatever you do eventually water will find its way in, then you can plan for it. For instance it would appear that water is trapped in each rib section, I think I would be inclined to either;
ensure that in future you have access to each compartment in order that they can be dried
or drill a hole in each rib, as low as possible and put a pump in the lowest compartment so you can get the water out. If you do this make sure you epoxy each drilled hole to protect the bare wood
good luck.

 

[Cret]

Thanks guys

This is what the layout is like inside:

Although the deck you can see has now been removed as it was utterly rotten.

I do have a bilge pump that I bought a while ago while I was accumulating bits ready for this job, then marriage/house/kids got in the way and the clock lept forwards 4 years!

Currently the rib sections you can see in the horror photo do indeed have holes from one to the next at the lowest point, in order that water can drain through if it gets in. I did this after removing the rotten deck and bailing out & cleaning these sections between the ribs. I think I painted them white inside since then (with Danboline I think?) to make them visually less horrible but it's a while since I've properly looked at the boat.

So from the comments so far it sounds like my best course of action is something along the following lines:

1) Remove the wood from the keel moulding. Replace it with a softwood beam, then secure with resin/glassfibre tape (or matting, is it important? Presume tape is stronger?)

2) Build a new deck (marine ply, sealed with epoxy) across the keel and ribs and glass over it/into the sides of the hull, but leaving it open at the fore and aft ends of the deck so that any water that gets in can either:

A) Air out easily if it's just damp or a tiny bit
B) Drain out behind the deck at the rear
C) Be removed by bilge pump if there's sufficient water in there

depending on the circumstances of water being there obviously.


Does that sound about right? If I do it this way then I'd have no means of inspecting beneath the new deck or anything like that, but if it's all well prepped inside there before the deck is fitted, and is open at both ends for air to get through will this matter?

I suppose it would be prudent to fit some sort of grills at either end where the openings are, to prevent any bits of rubbish etc from getting in under the deck and causing a blockage or something, but would that be enough to be confident the same problem won't happen that has happened this time?

I soooo wish I had access to the original designs of the boat to put it back how it originally would have been.

 

[oldsaltoz]

It sounds like you are about to spend a lot of time and a ship load of money.

Perhaps you should start by downloading the link below and reading the contents, it will give you a lot of very good information:

http://www.westsystem.com/ss/how-to-use/

Also note, many power boats do have Closed Cell foam under the deck, it's put there to provide buoyancy in the event of the hull being holed.

A relatively cheap alternative is the foam brightly coloured swimming pool sticks, packed into the compartments before the deck is placed. They provide buoyancy and leave enough space for drainage when required.

Do Not use Chopped Strand Mat (CSM) fibreglass cloth designed for use with standard poly resins, it will soak up 3 times as much epoxy resin as the cloth designed for use with epoxy resins, and may weaken the job.

Epoxy can be thinned by adding plain old Methylated Spirits to the mixed resin and hardener to help it penetrate timber.

Epoxy mixed with Micro-Fibres makes a super strong timber glue.

Any timber that is to be coated with an epoxy MUST be dry or you will simply trap the moisture and it will rot.

Before you do anything, you should sit down and do a full work plan and calculate the cost of all materials and the time required to complete the task.

I suspect you will find the cost of this project if done properly will cost a lot more than the finished item will be worth.

Good luck and fair winds.

 

[Cret]

Thanks for the info and the link. I do already use some West System resin stuff but the page you linked to looks very handy.

This work is going to be something that will take me a fair bit of time so I'm in no rush. I am very attached to the boat and it has an excellent engine with only about 40 hours on it so my money is in that rather than the boat itself. I already have probably about 50% of the marine ply I need for this, and many other fittings that are needed, plus have just bought all new bearings for my 4 wheel trailer, and a new set of wheels/tyres.

If there's one thing I've learned in the years I've owned boats (about 12 years) it's that trailers WILL bite you on the ass if you neglect them, just like boats will (just without the drowning potential), so I wanted to make sure that was right before bringing the boat back home to work on after its 4 year hiatus. At least that's taken care of now, and I'll be able to concentrate on prep work and clean up jobs which will have minimal outlay.

The end value of the boat itself doesn't really matter to me (I realise that may sound odd to some people) as long as it is sturdy and safe, and reliable. I think a lot of us have to accept that boats are generally money pits, and thus do this stuff for the love of it rather than as an 'investment'.

Progress will be limited since my free time is limited and my disposable income is limited and sporadic too, but this doesn't deter me at all.

 

[Cret]

This is more or less the structure at the moment (please excuse the crude diagram):

As you can see there are holes on both sides of the keel in the support ribs.
I added these holes after removing the old rotten deck.

My intention with the new deck is to build it more or less like this second image, below. The bottom left corner is the aft end of the boat, and since the fuel tank sits in one of these wells, I was going to leave them open as you can hopefully see in the pic:

The new deck would extend just inside the cabin, where it would be open again but with a movable panel sitting over the top to stand on.

So this way it is open to air at both ends of the deck so any water that finds its way in, can drain back out through the drain holes. If necessary then a bilge pump can get rid of excess water.

Does this sound ok?

The previous work done before I owned it was more or less the same except while it had open bits at the front (inside the cabin), the rear of the deck was fully sealed and there were no holes between the ribs. So somehow the water found its way in and was then trapped. I don't want to make that mistake when I rebuild it, but I think what I'm planning should be ok?

 

[Cret]

Actually, I've had an idea about removable deck panels which might work (I'm slightly paranoid about glassing the deck in place after the results I'm dealing with now).

Ok then, what I was thinking today would mean zero chances of having to deal with things going badly rotten in future.
The idea is that I would either run channel aluminium or L section aluminium along the hull where the edges of the deck would run, into which would fit removable deck sections. The below diagram is a bit basic - ignore the gap beneath the blue deck panels since I wouldn't obviously leave a huge gap there, but you get the idea hopefully. This is the hull, end on from the stern. Red bits are aluminium section with L section on the left and Channel section on the right (just to show different ways of doing this). Blue is the deck panels:

If I used channel section then the deck boards would be smaller and would be removed as required by sliding backwards from the deck area to the open rear wells. With channel section holding them in, there'd be no need to hold them down, simply something at the back to lock them in the channeling.

In contrast if I used L section (could actually just be wood, not metal) to seat them at the edges, they would simply lift out as required, which would be easier and less chance of anything causing them to become stuck. I'd use some means of pinning them down of course since they would obviously jump out of place at sea otherwise.

I recall my father's old boat (a 'Plastic Pig') used to have a deck like this, made of a few removable panels and it seemed like a good arrangement. The only thing that really would mean I couldn't do this, would be if it was totally necessary from a structural point of view for the deck to be glassed fully in place? Even if that was the case I would have assumed I could simply reinforce below the deck instead?

Really like the idea of doing it this way and the more I think about it the more it appeals to me as it means it's very easy to lift the deck if necessary to check the bilge. Seems like a big plus, but is there a particular downside to doing this?

 

[Cret]

Anyone?

Well, she's finally come home this afternoon, after replacing wheel bearings, wheels and tyres. Good to have her back home and can't wait to get cracking on the real work now!