once again i must ask the v20 gods
 

i have a starboard cover over my gas tank installed by the previous owner . now i find that no caulk will stick to statboard to bridge the gap between the gelcoat deck and the starboard, so now i am going to make a hatch from scratch, my question is can i wrap the fiberglass material over the 3/4 edge of the plywood or do i need to cut strips for that , or do i need to ease or round this over to some degree ? and how much of a gap must i leave so that when i wrap the wood with the fiberglass and the several coats of resin and gelcoat that it still lays in without being to tight. thanks for your help in advance . john,

If you want to get fancy with it make a mold to the exact outside demensions you want. Molds can be made from plywood laminated with formica use modeling putty for the radius and bend the formica for the radius corners . Glass the shell, add the core and glass the core gelcoat before or after for a factory like hatch. Lots of work and $$$ is the downside. Otherwise you laminate your precut plywood, leaving the plywood a bit smaller than your desired finished size (say 1/2" smaller than your opening)and work to it with glass and grinding. The top side radius and the corners of the lid will take the most time. You will not be able to make a tight radius with 1208 or any other multi-layer fabric IMO. You will need to do it with multiple layers of matt and hardware cloth. A 1/4" or less roundover bit on a router for the top edge all the way around would look nice and can be glassed without cutting into strips. You have to be creative on the corners sometimes. Wellcraft used a chopper gun on the liner and hatches, matt is close to the same when finished. Multi-layer fabric is great for the top and bottom. Be mindful of the thickness at the edge, Wellcraft did not run the core all the way to the edge on my boat. Measure the distance from the deck to the lip where the hatch will rest. It is probably only 3/4", meaning by the time you glass your 3/4" plywood on both sides your installed height will be higher than the rest of your deck. After you get the glassing done is no time to discover you have to grind it down to make it fit. BTW - NOT A GOD, bilge boy maybe. If you go for it post up some pictures.

hey ridge , thanks for the reply. i have no choice but to take on this project do you think i should double the plywood , not up to the supporting lip of course. but just to give the hatch more strength by having more density, and if so what should i use to join them together. and . it will be the last piece of the year long project, mymac helped me with re gelcoating the deck. i just wish i figured this before i gel coated the deck

I wouldn't double up. The fiberglass will serve to strengthen the plywood. Then the hatch gets screwed down and caulked in place. All of which makes it very sturdy. Do you have the cuddy or the center console?

after you get the hatch the way you want it, when you go to fasten it down, lay a couple of the foam noodles(cut to fit) across on the tank straps. i did this on mine and it cut down on the flex the will eventually lead to failure of the glass. it is good if it has to compress a little.

i have a cuddy

ridge, what do you mean by add the core ?

Core = Plywood. If you go to the trouble of building a mold what you make is the female version so when you lay the glass in you are really making the topside of your lid. Like they build hulls from molds. Gelcoat,Glass,stringers or core, More glass. You might want to look into some of the ready made fiberglass or composite panels. I never priced them but I have seen them online. Then you need only worry about sealing the edges and fitment. Depending on what you can find you could use some fiberglass tape and a minimal amount of materials.

ok thanks ridge, i will post pics when i get it done.

gas hatch
 

After getting advice from Ridge and phat i decided to go for a completely new build of my 34"x35". gas tank hatch. so today i built the mold for hatch out of MDF it was actually very simple to do, i have a question regarding Duratec. i understand it is applied after i have waxed and sprayed the mold with PVA. is the Duratec meant to adhere to the first coat of Mat or is it also just to keep the Mat from sticking to the mold? and do i even need to use Duratec .. i will try to get molding putty and all the other supplts this weekend. And yes i know this thread is useless with out pics. i will be taking pics of my rebuild. thanks guys,

no clue on the pva and duratec BUT if you have the clearance, a couple of 2" ribs made from ply strips glassed on the bottom on edge will REALLY stiffen the hatch.

hatch
 

Smoke, i am going to add a full size core to my hatch

yeah I got that.... I'm talking about a couple ribs in addition the the core glassed to the bottom of the hatch..... makes the difference between little flex and no flex

ok Sorry Smoke i got you now, thats a good ide. thanks,

Just be sure to test fit, dont want to have your tank cover higher than the floor.:beer:

PVA is the stuff that prevents things from sticking. Once your mold is built, wax the surface to make it slick, spray the PVA (mold release agent). The next application is the first thing you will see when you pop your hatch out of the mold. A guy on Classicseacraft.com used Duratec in place of gellcoat. It came out great. It would go PVA, Duratec, mat, reinforcement glass, core and more glass. The gent applied the Duratec and let it get tacky before he started to lay in the mat. He also had help because he was working on a large section (the entire sole)

I forgot who it was but they made a cover out of that plastic lumber that they use for decks, looked real nice!
On my Sea Ox I had to remove the cover to fix gas tank when I bought it, its a huge cover!! I say about 3 feet buy 6 feet, I call it the coffin as that's what it looks like (110 gal) Sea Ox used PVC pipe cut in half glassed under the cover to help with flex, floor is solid!

One other note is you will probably end up painting some sort of non-skid surface when you pop the product from the mold.

Again thanks for the help guys. I got it now Ridge, Duratec = primer. I think the gent you mentioned was Strick, what a talented guy. I still however am not sure about the molding clay, dues it get rock hard or do i need to press gently as i use the roller to remove the air bubbles? and i think i might use the factory grey color gelcoat that i have left over from redoing the rest of the deck this past summer. Cant wait to see how this comes out. thanks ,

If you can use the gelcoat that would be great. The modeling clay needs to be glassed over gently. It is tougher than you think. Yes, Strick definitely has skills.. Any updates?

hey Ridge, today i layed in the modeling clay and that was a job in itself, then i sprayed in a wax release. Tomorrow i will stop and pick up a Preval sprayer to shoot the PVA then i hope to have enough time to gelcoat. so yes i am moving along. I have one question though. strick mentioned that he does one layer of fiberglass tape over the modeling clay, do you think i can cut strips from my 3/4 mat or do i have to use the tape. thanks john

I think his tape is just mat tape. You can definitely cut the mat into strips for that. Any woven fabric there and you would be able to see the weave in the reflection of the gelcoat (print through). The roller type bubble poppers will have to be used lightly on the clay like you said. Have a brush ready to do some light dabbing. Oh and :pic:, Please.

once again
 

well i put a coat of unwaxed gelcoat on the mold today then i ran 2 inch strips of fiberglass tape and resin around the entire inside corner of mold over the molding clay . next i layed in one layer of 1 1/2 oz mat with resin ,had to stop thier because i had work to do that actually pays. i really wanted to put on another layer of glass just so i wouldn't have to sand between coats. It was hard to do but not as hard as i thought it might be. i will say i am so glad i bought the rollers to roll out the resin, that would have been a disaster, i took pics of the whole thing so far but left the camera at work or i would have tried to post them here tonight, i'll try and post them tomorrow night beacause as we all know:thre: lol

With the help of Ridge and after many pm's Here are some pics of the build of my new 36x36 gas tank hatch. one is of the mold built from MDF. then youl see the modeling clay used to soften the corners and radius's. then layup using 2 layers of mat Tomorrow iwill be adding 5x5 pieces of plywood core with a mix of cabosil and resin and more mat . also spray wax and PVA was used thanks to the Preval sprayer, the mold was then gelcoated prior to layup. you can see the old starboard hatch in the background.
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:clap:

Nice work. Your filleting work looks clean. Radius looks big, 1/4"? I am anxious to see how the gelcoat is gonna turn out. That is the one step I never tried. :clap:

Ridge, actually i made the radius even tighter after the picture was taken, it looked to be a bit to wide . i ran out of resin and got bored so i popped one of the side pieces of the mold off, it came rite off i couldnt believe it

So I am very intrigued about making molds,and this gives me motivation to try making a couple hatches. So let me try to understand, you build a jig or mold then round off inside corners with molding clay then spray with a release wax. You then roll out gel coat and then make your glass layup? Not trying to hijack thread please pm with details.

hatch
 

So i finished the build of my Hatch today. now here i am like a kid at christmas time , cant wait to get this thing out of the mold so i'm now working with the mold removal wedge and nothing and i mean nothing is happening at all. After about an hour i get the Hatch out , only problem is 90 percent of the MDF is still conected to it and i thought i used enough mold release but that spray wax the guy sold me must not have worked. Now here i am taking the MDF down layer by layer 1/32 nd of an inch at a time with my Dewalt power planer. Just wanted to shoot my self. so after three hours of the Planer the palm sander and 4 different wood chisels i got it down to the gelcoat but not without a little bit of damage. i did expect that it would need some work but not the 2 gouges i put in it! The point of the story is hand rub the wax into the mold. other than that the hatch came out fantastic could not be more pleased

Congratulations
 

Post up a picture of that bad boy. Good talking with you too BTW.

you can use hair spray as a release agent

hatch
 

Spare, i did not know that one , I'll keep it in mind thanks. But next time i will be using Formica for my mold material so that wont happen again. I just finished gelcoating the hatch this morning and it looks good ! I us a textured roller that is made for applying contact cement,it has a slight stipple to it and lays down a very nice pattern. Ridge i really enjoyed our conversation yesterday as well, thanks again. I will post pics of the finished hatch this weekend.

once again i must ask the v20 gods
 

Ok so here is the finished product, 1st as you can see is the core. then of the mold removing disaster, scratches from the dewalt power planer that i had to use to remove the MDF, then used poly filler to repair, then re gelcoated with stippled roller used for applying contact cement.







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Yup!!...that really looks great!!...nice job...:clap:

It turned out great. It should offer more grip and strength than the Starboard.
AND The coring was done right IMO. Leaving the core just shy of the outside edge is a strength multiplier. The glass that gets put over that rounded edge and back up the lip forms a much more robust design. Another advantage is upon screwing the lid down around the perimeter, no screws will be into the core. You just want to make sure the hatch face is thick enough in that area to be able to easily countersink the screw heads. That is where Whaler has screwed up on their lid and hatch design IMO. They run the core to the outside edge and then proceed to fix brass nuts in place to be fancy then the back side of every lid is glassed over and gelcoated. They rely on caulk around the fasteners to keep the water away from the core, same holds true with keeping water away from the foam sandwich construction in all the thru hulls.
It looks nice and foo foo having a slick gelcoated back on all the hatches like the Whaler lids but several lids failed at about the 6 year mark due to their construction techniques. I built my hatches like yours and they are already older than that ,still perfect.

hatch
 

and now i can seal the gap between the hatch and deck and not have water dripping on my gas tank .:time:

The hatch fit like a glove , how funny is it that 3 weeks ago i had no clue how to do this and today i have a costom built hatch . now i start on my helm seat box with tackle storage :head:

can anyone tell me how wellcraft origionaly fastened these gas tank hatches . Was it countersinking the screw heads or using SS finish washers. Thanks