Raise deck fittings or leave them flush?

[Wind River]

I am just about ready to lay fiberglass over new newly cored deck.

I have seen some boats with their deck fills and fittings raised up about 1/2" above the surrounding deck and most hatches seem to be this way.

I assume it is to keep water from standing at the fitting? Is there any other benefit to this or drawback?

If you were to do this, would you do the deck layup first and then add some core material to the area of the deck fills and glass again? or add the core material first and glass over the raised area.

How high above the surrounding deck would you go?

Or would you even spend time on this at all?

[GordMay]

I prefer all* deck penetrations to on/thru raised housekeeping pads, for the reasons you stated.
* Fills, Chainplates, Cleats, Winches, Deck Organizers (Turning Blocks), Helm Pedestal/Tiller, etc.

[coopec43]

When I laid up my deck I put in a marine ply pad for all deck fittings and fiber-glassed over them (and the divinycell core). In retrospect I should have raised them more than the 1/4 in. I did .


Clive

[Wind River]

Thanks Gord and Clive.

I was leaning the way of raising them a 1/2" or so.
I am using Coosa Board for my core and it doesn't hold screws well. I will try to through bolt them if I can, if not, I will pot them with resin and glass.

Any other thoughts on this?

[coopec43]

Originally Posted by Wind River

Thanks Gord and Clive.

I was leaning the way of raising them a 1/2" or so.
I am using Coosa Board for my core and it doesn't hold screws well. I will try to through bolt them if I can, if not, I will pot them with resin and glass.

Any other thoughts on this?

Well I wouldn't screw any deck fitting on to deck: it must be through bolted. A stanchion just wouldn't hold if it was screwed and someone went sprawling across the deck and hit it.

Undoubtedly you will use a combination of what we call Chopped Strand Matt (CSM) and Woven Rovings (W/R) to lay up your deck. W/R doesn't take well to right angle corners so it will be necessary to radius the corners of each deck pad. Once I had cut each deck-pad I then used a thinned resin to "prime"each one.

I did the "form-work" for the deck, laid up the first layers of glass, then positioned every backing pad and rosined them in place.

The divinycell core material was then cut to shape and fixed in place using Divilette putty. I wouldn't try to lay large areas of core material in one operation as you would probably end up with areas with voids - where the core material is not in contact with the glass. (I used a rubber mallet to ensure I had good contact)

If, after laying the core material the was a slight un-eveness, you could give it a light sand but the un-eveness would undoubtedly be lost in the subsequent fiber-glassing anyway.

Clive

[billknny]

Originally Posted by Wind River

Thanks Gord and Clive.

I was leaning the way of raising them a 1/2" or so.
I am using Coosa Board for my core and it doesn't hold screws well. I will try to through bolt them if I can, if not, I will pot them with resin and glass.

Any other thoughts on this?

I don’t care what kind of coring you use, you should ALWAYS isolate holes into the core with an epoxy plug. If you do not water WILL get in there.

If you use heavily filled epoxy, you can screw into it for things like deck fills, but hatches and stanchions and other load critical things should always be through bolted. Anything else is a shortcut.

[coopec43]

As I didn't raise the pads high enough when I fiber-glassed the deck I have made up plastic/nylon(?) pads for all the stanchions.

The pad pictured has been slightly tapered to make the stanchion stand upright. I will use a flexible sealant like Sikaflex 291 when I install them. (Most pads are thinner than the one pictured as they didn't require tapering)

[coopec43]

I should have mentioned the "plastic" I used came from a recycle bin located at a specialist plastic fabrication/signwriter's outlet. I often got scrap plastic which has been very useful during construction.


Clive