automobili_v12

How Heavy is an Engine Hatch on a 1990 Top Gun?
Has anyone tried to lighten them up?

Feels like it weighs 500LBS

seafordguy

It probably doesn't weight quite as much as my Cafe Hatch since it doesn't have the "edges" down it, but I bet my Cafe hatch weighed 400 lbs!!

Get 6 or 7 guys to help you if you don't want to take the chance of dropping it.... (Or pull it off with a lift)

UrbanDisturbance

When I was getting my Arneson drive conversion on my 1994 Cigarette Top Gun, we took the hatch off. I think there was 6 of us moving it. It is very heavy. I remember almost dropping it. I bet it ways more than 500lbs. I think making a lighter hatch would be a great idea. You may gain 4-5 mph. I would do it, but I was ordered not to spend anymore money on the boat.

automobili_v12

This thing is either full of water or full if steel.
We couldnt believe how heavy it is.

What is the core made of?
Has to be plywood or pure glass, dont see Balsa weighing that much

EXCESS ENERGY

iTrader: (2)

Should have bought my hatches. About 75lbs each. And strong you can walk on them.

glassdave

iTrader: (1)

my Twin Step hatches are about 110 pounds but are a more technical and a lighter lay up then Cigs, I could easily get the weight down to seventy pounds or so and still be plenty stiff/strong. Last couple of factory flat hatches i remover were an easy two hundred plus, the latter being a 99 and it was no lighter the the 90 i have in the parts pile.

cafe man

Hi guys. The theme weight- reducing at older cigs is very interesting.
I was also amazed about the weight of Café - hatches . But i think they are hard to replace because of the complicate fit. -but another interesting point is the weight of the cockpit-floor. That thing is also heavy like a tank! - but have a simply geometry! I belive, ther you can save a lot of weight with the right material.
Chris

tcelano

Hi Guys. The one I built for my mistress is prob right at 200 lb, and plenty stiff. My blower scoops aren't meant for walking on but everything else is bomber. I ran a 2x6 spar with a 2x4 flange to soften it against the ply and provide a good land for a plywood seam right down the middle. The layup was pretty light, like 2 layers of boat cloth, and I threw on a sheet of carbon I had left over from another project. Mine sits on top of a flat deck, so I used 2x3 around the bottom perimeter, and bent to match the deck crown. I routed a channel in the bottom of it to stick in a bulb seal. When it Is down the gap is small, but the hatch is on the seal so no abrasion. Since I don't want it to twist off the hinges in a good side hit, I installed some 1/2" bolts with acorn nuts sticking up. I drilled the hatch bottom up forward to land on and engage on those. With the hatch actuator sucking it down, it's not going anywhere.

Like Dave says, if you really wanted to get serious and use high tech cores instead of junk lumber and ply, you could make one incredibly light. Most likely though, you will need a mold to do that. My one-off relied on the plywood for shape, as I computer lofted it, then pasted on printed templates to make the developed parts.

automobili_v12

What is the Core in the Engine Decklid and Cockpit Floor?

What layup and Core can I use to make lighter Parts?

tcelano

Common cores for use above the waterline are divinycell and balsa. Honeycombs are often used for decking, but are difficult to bend to any shape, and have dubious resin absorption and bonding issues. Like I said though, these things work best when you can lay down the outside skin in a mold, and then properly bed the core to the laminate. You have to have a good bond capable of handling the shear loads for the cored structure to be any good.