Anyone ever made a lightwieght engine hatch???
 

My sunpad/hatch will soon need to be recovered and that thing wieghs a TON!!.......Seeing its needs recovering anyway Im wondering if anyone has ever made a lightwieght hatch that stands up to three or four people sitting on it.....Ive heard of people using some stuff called DecoLite..... Can this stuff hold up???.....any other ideas???

Re: Anyone ever made a lightwieght engine hatch???
 

Simply getting the water-soaked plywood and foam out will cut 1,325 pounds, and gain you 17 mph, with a margin of error of 1,300 pounds and 18 mph.


I used HDPE, commonly known as starboard. While it is not light, it won't ever absorb water, and upholstery staples stick in it very well. For more weight savings, ditch the upholstery, and use carbon fiber or Nida-Core honey comb rigid material, with gelcoat to match your boat.

Re: Anyone ever made a lightwieght engine hatch???
 

Chart- I take the batteries out for the winter so I have to disconnect the ram and muscle it .......Im 6'2/ 230 and its EVERYTHING I can do to lift the hatch without the ram.........believe me........if it ever hit you in a freefall it would litterally kill you........US1 took his off and it took 4 guys just to lift it......Its gotta wiegh 400lbs......what thickness of starboard did you use????........did it hold up to people sitting on it?????......doug

Re: Anyone ever made a lightwieght engine hatch???
 

I just had to replace all the wood on mine, and that thing took four guys to take off!!!

Re: Anyone ever made a lightwieght engine hatch???
 

Hopefully this thread will get lot of response and pictures. When we took mine off to remove the engines we used a fork lift. THere no reason for the thing to be that heavy--and it would kill someone it it fell--

The Starbord is easy to reinforce--similar to shat I did on swim platfrom I buit could use 1" starboard and strategically placed 1" X 4" stringers glued and heat bonded together. Swim platform is 72" X 30 and wiegsh about 80 puounds.

I've got access to a starboard/acrylic fab shop here that will make them if we can get templates.

Re: Anyone ever made a lightwieght engine hatch???
 

Cuda and I have the same boat, Formula 302's. He's got a few pictures of the work he's currently doing, and I'll look for some of mine later today after actually doing some client work.

On our boats there is a molded fiberglass tray with reinforcing ribs designed in it. The upholstery parts lay on top of the tray, and are screwed in around the parameter. The lifting ram is attached to the underside of the fiberglass tray.

From the factory the upholstery parts included marine plywood backers and foam and vinyl. Over the years the foam and plywood absorbed water, even though there were drain holes in the tray under it. That is where the weight was lurking, the waterlogged plywood and foam.

If you are going to use upholstery material, you need something to hold the staples, either plywood or HDPE or roto-cast plastic or something similar. I chose HDPE because it was available, machined very easy with wood tools, would never absorb water, and the marine grade plywood Formula used ONLY lasted 19 years :rolleyes:. Might have lasted longer if it hadn't gotten as wet as often, but it's a boat that that's going to happen.

I used 1/2 inch HDPE (High Density Polly Ethylene(SP?)) which came in a 4.5' x 9' sheet. Don't know why they use that size, and I had to use a utility trailer to go get it, as that size don't fit in an Excursion. It's not light, and it's slick, so strapping it on the trailer was interesting. I THINK DecoLite is a LowDPE, and it should also work as an upholstery backing board, but won't provide the same structural strength as HDPE. [on edit: DecoLite is different from LDPE, and should provide strength if prepared corectly]

On the 302's, there is a lip molded around the opening to the engine compartment which the sundeck rests on when closed, so the sundeck is supported all around the parameter. With the fiberglass tray and the 1/2 HDPE screwed together, supported all around the edge, it's plenty strong for a couple of people to lay/sit/walk on, without much give. BUT, I walk close to the edge as it's weakest in the middle. If there were a couple of drunk topless chicks who wanted to dance on my sundeck all day long, well, I'd let them, but would expect to have to repair it before the next weekend when they would be welcomed again. After all, isn't that what sundecks are for? In a perfect world they would not be heavy enough to hurt the sundeck, so it wouldn't be a problem. Okay, back to reality....

For true light weight, consider NidaCore. It's a very strong honeycombed panel with thin fiberglass skins. It may be avable in other skins too, which might better take staples. I'm using this material to very very slowly build a race faring to replace the windshield. Jetliners use a similar material for floors, as it's strong and light. I can try putting staples in my NidaCore if you are interested, and have a way to get it. It's pricey compared to HDPE, but you'd only need one sheet either way. Personally, think it's overkill in this use for a pleasure boat, but if you are racing then every pound counts.

Finally, I've only got one season on my sundeck, including the winter. It's held up wonderfully so far. I was concerned about shrinking in the cold, as I calculated it might shrink by 1/2" at most during the cold winter months. That does not appear to have been a problem though. I built it during the hottest months of the summer, and made it as large as possible to allow for the possible shrinkage during the winter lay-up. HDPE works well with mechanical fasteners, (screws, staples, brad nails, etc) but pilot holes are suggested for screws, and don't torque down on them for the HDPE will strip out. Glues are hard to find to work with HDPE, and "welding" works better. The few glues I've heard about chemically melt the HDPE and then it bonds together during cooling. These glues are very expensive. The local water department uses HDPE pipes underground in 40' lengths, and they have a special "welding plate tool" that melts the ends of two lengths and then holds them together to cure. Lacking anything like that, I just used a bunch of ss screws instead.

In addition to the sundeck, I rebuilt the back seat with 3/4" HDPE instead of marine grade plywood. At that thickness, with the proper bracing and supports, it's quite strong and looks great. Instead of carpeting the exposed material as the factory did with the marine plywood, I left it exposed, and it gives the boat a nice updated look. The upholstered seat bottom was made from 1" HDPE, as were the headrests, and that's plenty strong.

This has been a lot to read, but if you're still awake and have any questions, just ask.

Re: Anyone ever made a lightwieght engine hatch???
 

I've done a couple. The biggest on a staggered 38'.
1/2" plywood on top, 1/4" plywood on the bottom. I used 1 X 2s to fram in between. Covered the whole thing with a layer of glass and resin. It's not rot proof but I've noticed the way uphostry is attached/sewn probably has more to do with that than the materials.
Gary

Re: Anyone ever made a lightwieght engine hatch???
 

Twinn29,
We're building one now for my twin 29. It's starboard with Birch stringers. I wanted a light hatch with scoops that would take the load of two adults. This things strong. We had two big fat-azz Kiwis standing on it without braking. I'll snap some pics this weekend for you. It took about 400lbs off the boat too.

Re: Anyone ever made a lightwieght engine hatch???
 

Baltek Decolite panels would make a good, fairly inexpesive hatch. It's about as strong as an equivilent thickness of plywood. The fiberglass covering is thin, so you'd need to glass over it again to toughen it up. Add a couple of ribs under and your all set.

Re: Anyone ever made a lightwieght engine hatch???
 

Ian where can you get this stuff and what does it cost? I always wanted a smooth hatch with scoops but the wife would kill me but I could make a spair with scoops and use it for Poker runs and stuff.

Re: Anyone ever made a lightwieght engine hatch???
 

looking forward to pics from all.....Starboard sounds good cause I know I can get it around here....Chart:where would you get HDPE??? Id like to check it out........Lofty: did you really save 400lbs??......that would awesome..........doug

Re: Anyone ever made a lightwieght engine hatch???
 

I just got done removing my hatch to install two scoops on my Daytona. There's two sections, the actual molded fiberglass hatch that the hydraulic ram is attached to and a sheet of padded board that's bolted to it. I would have to guess the two pieces together weigh 150-200 lbs.

Re: Anyone ever made a lightwieght engine hatch???
 

More or less, Starboard is HDPE. I started out looking for Delrin(sp?), because I knew of a guy who had used it for upholstery. Yikes! That stuff is expensive! Then I started looking at Starboard in marine catalogs. Luckily I could not find Starboard in large enough panels, and had to do research that involved calling a plastics trade org and a professor of plastics chemistry. The end result was a recommendation of HDPE. I then ordered small samples from Granger or McMasterCarr and experimented with them. Tried machining them with wood tools, worked great. Clamped a two foot piece vertical in a vise and secured 30lbs of weight on top of it overnight. Held great. Then I called a local plastic dist. from the yellow pages, and told them what I wanted. Said "sure, we stock it. Do you want it in UV resistant or not? Do you want a matt finish or not?" There's was called Boatboard. (At this point I figured out Starboard = HDPE) It was under $300 for both sheets, but I think others elsewhere have gotten much better pricing. Give me a little time and I'll get the pictures up.

Re: Anyone ever made a lightwieght engine hatch???
 

Don, there's a place near Detroit called Michigan Fiberglass Supply. Sorry I know that's a hike for you. I could haul it up on Smoke weekend.

Re: Anyone ever made a lightwieght engine hatch???
 

I was just there Tuesday picking up supplies for my project Correct Craft. I almost drove right past it, but the guy there was very helpful in suggesting what I needed to get to finish the job. Fiberglass, resin, adhesive for bedding stringers, etc.

Re: Anyone ever made a lightwieght engine hatch???
 

Sorry for the delay in posting pictures. Between forgetting, and traveling, it took a while. HDPE machines very easy with wood tools. I used table saw, miter saw, circular saw, jig saw, and drills, all with nice results. One aspect I really liked was the lack of air-borne dust like wood produces. This came off in shavings, and all fell to the floor.

In my sundeck, I built headrests, and most of the pictures are off cutting those out with a router and template. To get the correct shape of the HDPE, I simply laid the fiberglass tray on the HDPE panel and traced. It's important to mark which side touches the fiberglass, and which side will touch the foam. Nothing on a boat is symmetrical, including the sundeck.

I also beefed up the fiberglass sundeck in the corners where the hinges attach. Doing fiberglassing where it doesn't show is a lot more fun than doing fiberglassing where it does show!

Re: Anyone ever made a lightwieght engine hatch???
 

Here shows the fiberglassing, and the almost finished sundeck with the upholstery on the boat. I was building and test fitting the headrests at this point. My upholsterer was a joy to work with, as I'd bring some of the work in, he'd do it and I'd take it back for test fitting the next parts. It's easier if you go back with just as it was stock, but I wanted big changes.

Re: Anyone ever made a lightwieght engine hatch???
 

Thanks for the pics Chart!!.......I called around......Starboard is readilly available around here........
How heavy do you think the stock fiberglass tray is.....all by itself???
Do you think you could save much wieght by making a whole new one out of HDPE and simply upolstering it and covering the staples on the edges with a piece of trim???......doug

Re: Anyone ever made a lightwieght engine hatch???
 

PMT: No. I recall the starboard to weigh more than the fiberglass tray. You won't get much weight savings by eliminating the tray, especially if you have to reinforce the starboard to support people on the sundeck. Keep in mind, my tray does not have a piece of plywood glassed into it, like the floor of the boat does. I don't know if your boat does or not.

How many pounds do you want to save anyway? How much does your tray weigh? I could easily lift and move each part by myself, tray, 1/2 inch starboard, foam, and vinyl. I doubt the whole think including s/s screws weighs 100 pounds. Getting the old waterlogged plywood and foam out was the biggest weight savings.

Re: Anyone ever made a lightwieght engine hatch???
 

I havnt tore into it yet (have to install new twin elect silent choice and re and re the k planes to have them blasted/painted and change the rubrail first :D ) but I do know as in my first post that hatch is EFFIN' HEAVY!!!!........were probably looking at the middle of the summer before I can get to it as I have to work outside and its borderline snowing up here still......my boat is an 89' so it could very well be all waterlogged wood......doug

Re: Anyone ever made a lightwieght engine hatch???
 

I'm ready to build my engine hatch. It is about 7'wide and 3' length and is supported on the sides and back( not the front). I am thinking of using 3/4" starboard or starboard XL white. I need to buy a sheet of this, Does anyone have a good supplier for this? And price and shipping to Philadelphia PA area. The best I found is from Total Plastic for a sheet of starboard XL 60"x96" sheet for $323 + shipping of ?$100-150.

The starboard XL is a little lighter than the std. starboard. 3/4" is 109 pounds vs. 135. The piece I need is about 21 sq.ft. so about 60 pounds vs. 80 pounds.

Re: Anyone ever made a lightwieght engine hatch???
 

Cobra: Check out post 13, unless you got money to burn. The lighter starboard may be less dense, and therefore offers less strength, if that is required in your case. As your's is not supported in the front, I'd think that is the case. Can you attach a backing board or support under the front of the sundeck to add strength?

Re: Anyone ever made a lightwieght engine hatch???
 

heres my 2 cents Starboard and HDPE are not the exact same they are similiar HDPE is somewhat cheaper but can be attacked by the sun . Starboard is more expensive and resist the sun but since it wil be covered by the sunpad that is not a concern, I used the hdpe on my hatch and seats ect. this is the way to go, just my 2 cents.

Re: Anyone ever made a lightwieght engine hatch???
 

did you make a complete new hatch.....or did you replace the wood in the fiberglass tray??........doug

Re: Anyone ever made a lightwieght engine hatch???
 

Codered: The local plastics dist stocked HDPE in both UV protected and not, and Matt-finished and smooth. I only requested HDPE, and they asked which types I wanted. So, in it's purest compound, it's probably not UV resistant, but it was easy to find HDPE that is.

BTW, a lot of plastic cutting boards are also HDPE, as it is food-safe. Most of these are white, and seldom discolor. In fact, I think the cutting boards at Subway sandwich shops are too (just a guess).

Re: Anyone ever made a lightwieght engine hatch???
 

I found a local plastic dist. 20 minutes away who has a 4'x8' sheet of HDPE 3/4" white for $176. I think that I'm off to get the material to build a hatch.

Re: Anyone ever made a lightwieght engine hatch???
 

What about scoops? Any recommendations on scoops that'll hold up? Important as a lot of time is spent partying on the back so it's gotta hold up to the occasional drunk.

Suppliers? Prices?

Re: Anyone ever made a lightwieght engine hatch???
 

The stuff I used was called Shipboard, supposedly the exact same thing as Starboard, but less money. I used the light stuff. Real easy to work with. I used a leftover piece to rebuild the swim step on my fishboat.

Chart, what bit did you use in the router?

Re: Anyone ever made a lightwieght engine hatch???
 

Here's my tray and the shipboard layed in to check on the fit. I should have the upholstered pad back this week.

Notice the aluminum stock to strengthen the hinge areas. I have some quarter inch Hardiboard to bring the other areas up to the same height.