Hatch garage and hard doghouse…screwed down or through bolted?

S

steve yates

Well-Known Member
Joined
16 Oct 2014
Messages
4,114
Location
Benfleet, Essex/Keswick, Cumbria
Visit site
Having just drilled, decored and filled out 145 holes in my Longbows deck, due to cabin leaks and patches of rotten core (all replaced now) from deck fittings, I have discovered that the primary culprit was the hatch garage and grab rails. The dog house was only a minor contributor, though I had suspected it was the main cause.
I was surprised to find that both hatch garage and doghouse were just screwed into the deck and am inclined to through bolt them with large washers when I put them back.
Any particular reason why I should just screw them down like previously? Apart from laziness as it would be simpler not trying to be in two places at once if bolting them :). Am I overthinking the idea they should be through bolted?

Thanks.

Ps, I had thought that westerly used encapsulated nuts with their hatch garages, and indeed in my original hunt for leaks I unearthed one, but on removing the garage and drilling out all the holes there were no more to be seen.
 
If you drill the screw holes well oversized, then fill the hole with epoxy, then drill for the required screw size, you will get a strong fastening that will not leak through if sealant fails.

West System GRP Repair Manual details. Google it if interested.
 
The hatch garage is usually just screwed down by Westerly as it is not under any stress. All the original deck fittings were glasses over before the deck was fitted to the hull. The hull joint was then glassed over for a completely waterproof joint. Later owners frequently did not understand that balsa cored areas needed reinforcing to stop the two layers of the deck compressing under load, which causes the sealant to breakdown and ultimately water enters and rots the core. Westerly did fit plywood pads instead of balsa core in expected areas for fittings like an anchor winch, midship cleats, spinnaker blocks, etc.

You mention a dog house. I am sure this is an owner fitting. This should be through bolted as any large surface area can take immense loading if hit by a large wave. On my Fulmar one large wave pulled out the screws from channel holding the sprayhood lower edge from the teak wave break rails. The original supplied screws have now been replaced with much longer ones. If it can happen on a sprayhood, imagine what could happen to a dog house.
 
RunAgroundHard said:
If you drill the screw holes well oversized, then fill the hole with epoxy, then drill for the required screw size, you will get a strong fastening that will not leak through if sealant fails.

West System GRP Repair Manual details. Google it if interested.
Click to expand...

Just to mention that I don’t need the info about overdrilling filling etc, as all of that I have just finished doing. (Westerly evidently didnt do it with the hatch garage and the doghouse was added by a yard at previous owners instructions, and they obviously did not do it either.)

Just trying to decide on best way to refit said items. Leaning towards screwing down the hatch garage but bolting down the doghouse.
I think I’ll go with butyl tape as a sealant between the deck and the flanges, as well as for the screws/bolts.
 
Last edited:
Butyl good.

Regarding bolts or screws… are you questioning structural integrity or security?

You will not be taking the seas of the Southern Ocean over the top I guess.

Security seems a non issue from responses from this forum; I agree with the forum - thieves will get in and the amount of destruction is noteworthy.

Therefore I conclude screws.

I am not a nautical engineer, however.
 
steve yates said:
Integrity, not security .
Click to expand...
In that case there are various designs of screws just to make things even more complex.

The new designs of screws does annoy me at times ( because of my lack of of knowledge - if I wish to be modest).

I am not helping I feel;

Bolting is always my preference with penny washers in many circumstances, but I believe (I am no expert) in your situation that with good screws, butyl and filling compound, you will achieve a good waterproof job - you sound like you are on top of things anyway.

Maybe someone more expert will be along later with expert advice meanwhile, stay dry 👍
 
I built a doghouse for our cat helm station. The last part of building was to drop the completed structure on to a large bead of uncured, filled, resin, separated from the original gelcote with packing tape. This then formed a perfect mating, flanged surface. When set I ground off the excess and covered the overlap with glass, then filled the texture and sanded. I then attached the final structure with Sika and screws into the foam core.

It with stood seas breaking over the top of the structure for one eight hour period crossing Bass Strait with average winds of 55 knots and peaks off the scale of our instruments. Our doghouse was 3m above normal sea level, most yacht doghouses are locate much lower and will be impacted more violently and forcefully than ours

If you are worried about the integrity of your structure in terms of its attachment to the yacht - you need to also ensure that the structure itself is strong enough. Windows are potentially a weakness, ours were acrylic. framed and set into matching frames built into the structure.

Making a flanged interface means lifting the 'completed' doghouse on and off its location. Its not a single handed job - you need to get it right first time - or it would be a bit of a nightmare. We needed two people to lift the doghouse comfortably and another person to ensure it was dropped on the, large, bead of filled resin precisely.

Jonathan
 
My inexpert and initial reaction would probably favour bolting, but I'd guess there is no right answer.

One thing giving me pause is the potential consequences of a bolted doghouse if it carries away anyway, which is going to make BFH's (or worse, A BFH) in your coachroof, just when you especially dont want them/it.

I suppose there is an argument for making a doghouse more of an expendable item, though understandably you wont want that to apply to you if you are inside it.
 
You must log in or register to reply here.

Share this page

Top