Hatch door repair

[Aquamaniac]

Have a front hatch door that seems to have cracks in gelcoat and core issues. Thought it would be a simple fix....just cut out the core from underneath. grind things smooth, glass in a new piece of plywood, then fix gelcoat. The core area is roughly 14x40.
Here are a couple pics......



In my usual fashion, the more I tried to get a clear plan together, the more confusing it got!
Have read a lot on 'glassing in a new piece of plywood' .....and it is anything but simple. 

What resin, what glass, what wood....or even wood at all?????

The underside of the door also appears to have layer of gelcoat(?) which might complicate matters.

With all the experience here on rebuilds, I figure there must be someone who has dealt with this and can point me in the right direction.....'cookbook style' as I am pretty much a novice with fiberglass.

Thanks!

[RickK]

This is what I would do and did on my front hatch.  I would use a cutting wheel and at an angle at the base of the wood backer I would cut into the wood where it meets the gelcoated aft of the hatch all the way around.  Now it is only being held by whatever they glued it to the hatch with.  Stick a good breaker bar in the cut and gently pry up the wood.  It should come up easy enough. I show how I did it starting on this page of my rebuild http://classicaquasport.com/smf/index.php?topic=10101.690.

As for wood for the backer, that is fine.  Just make sure you seal it up real well and then cover it well with glass.  I used composite for the backer because that was the plan for the rebuild.

[RickK]

As for the cracking in the face of the hatch, that's a different story.  Make sure you reinforce the back of the hatch with a couple layers of glass to beef it up.  Then I would think about roughing up the casting deck totally (including this hatch) and then using this method http://classicaquasport.com/smf/index.php?topic=1991.0 to put new non-skid across the entire casting deck so you're not trying to match the existing pattern.  It's real easy to do and you have control on the amount of non-skid you apply.  I am going to do this approach on the entire inside of my 170 when it's done.

[Aquamaniac]

Hey RickK,
Thanks for the info and link. Love the non skid.
Got what might be a pretty basic question....in laying up the layers just underneath the top for reinforcement, what resin should I be using? You used epoxy. Guess I am pondering if any leaks through the cracks, I don't want to have an issue with gelcoat not adhering. Poly or vinylester for everything?? (including wrapping the plywood.) Any specific recommendations on cloth.....I did see your schedule on your rebuild.....any different with wood vs composite?? Also....what did you use to finish under the door once completed? Epoxy paint? Please bear with me....just learning. Thanks!

[RickK]

This is a pretty small task so you're probably not going to want to buy epoxy to do it, it's expensive and to have extra around is not cost effective.  (You never said how big the hatch is) I'm not sure what the smallest amount of epoxy kit you can buy - maybe a gallon?  You won't need that much for sure.  So I think I would go poly since you can buy it much cheaper at a supply house or buy two repair kits at HD.  If you can find an epoxy 1/2 gallon kit you might consider that. You're going to have to find a fiberglass supply house for the cloth so see what they offer.  Also you'll need a small amount of cabosil to make some thickened resin to trowel on the wood to stick it to the hatch.
As for cloth you want something that will give some strength, maybe some 1208 or 1708 - 2 layers so buy a couple yards of that - it comes in 30ish and 50" widths. What you want to do prior to any of this is to see how the hatch cover sits on the receiver - does it touch the top of the receiver? If it does you don't want to build up the thickness of the hatch itself much otherwise it will not sit flush anymore.  Something to think about.  When you lay the cloth put the matt side down.
Some people score the plywood the allow deep penetration of the resin when they coat it - you can try that or at least make sure you have the piece covered well, especially the end grain. Cut the edge of the plywood at an angle so the cloth will traverse it easily and then coat it with the poly. You'll have to do this in two steps, one for each side. Let the wood and the reinforcing cloth on the back of the hatch cure and make sure they are flat.  Take a grinder and lightly scruff them up prior to adding the wood.
To stick the wood to the hatch mix up some poly or whatever you decide to use with cabosil, after you add the catalyst, and thicken it up to peanut butter thickness and then use a cheap tile trowel - 3/16" or 1/4" notch to spread it on the back of the wood and then position it where it needs to be on the hatch and put a couple cinder blocks or whatever you have around to weigh it down on a flat surface.  Let it cure.
Then to tie it all together a layer of 1208 or 1708, matt down, over the wood and onto the hatch lid. You'll have to cut the cloth here the angles meet on the corner of the wood, to get the cloth to transition.  Cloth does not like corners.  Do this prior, obviously.
For coating the finished work, if you used poly you can buy a qt of gelcoat and roll or brush it on.  If you chose epoxy you'll have to paint it or use epoxy paint over it.  I will use epoxy paint on mine since I used epoxy.
Hope this helps.

[Aquamaniac]

Hey RickK,
That helped a TON.....thanks!
Been reading more on your non skid approach and the various alternatives. Basically trying to figure how best to deal with the top side, once structurally the door is solid. Seems like if I rolled gelcoat in the non skid area of the door (which has the spidercracks) it would fill the cracks (especially if I gouge them a bit bigger). Then come back with the textured gelcoat. From what I have read, texture paint (Kiwigrip, Duraback,etc) would fill the cracks, but then on I am stuck with paint. The paint method sure does seem easy.
Thoughts?

BTW.....the 'core' area of this hatch door is roughly 14x40"

Thanks again!!

[Aquamaniac]

Another thought to run by you......
What about reusing the glass that you cut away when extracting old core? If it could be cleaned up inside and out. Lay the prepped wood into that....using the thickened resin to bind. Then set this 'assembly' onto the area the old core came out of.... using the wetted reinforcing cloth/ thickened resin first. Once that cures, add strips of wetted cloth around the perimeter to bond and smooth things out. Might have to add some thick stuff if any gaps.
Your point on how the door sets into the hatch is good. It does seem to rest on the upturned lip of the receiver....so need to be careful not to build up there and have door end up proud. The fact that I am into reusing whatever I can is really why I am pondering this....but it would ensure the fit.
Also wonder if laying up two additional 2"W slats of 1/2"ply in the long axis of the core would be a good plan to increase strength....or too overbuilt? Seems like a pretty long hatch to bear weight without flexing/cracking. Is this a chicken/egg issue....i.e. the poor support in original design led to flexing/cracking...which led to core rot????

[RickK]

If you want really strong go with epoxy.  I think that you will still get some flex - you could go with 3/4" wood. I would not bother trying to salvage the old glass.  You want the finished product to be all one piece.