solutions for opening heavy teak butterfly hatches...

[Cadence]

Originally Posted by Rowglide

I appreciate the simplicity of gas cylinders but they don't appeal to me aesthetically.

With a little ingenuity you could probably make them look nautical.

[S/V Alchemy]

Originally Posted by Cadence

Gas pistons similar to those used on auto (van) hatches would seem a rather simple solution.

That's exactly what I used on my 48" x 27" engine bay hatch. The engine was tarped to keep welding debris off it. The pistons work well:

https://www.youtube.com/watch?v=GbJt0VIh-8s

[TrentePieds]

This is the solution:

Quote: "We looked a boat a few years ago that used pistons to open the butterfly hatch, and had a sort of knotted pull string that could be used to set the opening height. We’re gonna try the same thing in the next week or two. "

It is important to use a mechanism that at no state of opening permits any part of it to protrude below the hatch coming/deckhead. Metal parts protruding below the deckhead can be deadly if you get thrown! The gas strut is a safe mechanism. By analogy to an electrical push switch, the hatch is "normally open", and at no state of opening does it stick down where it shouldn't. A lanyard is taken from the hatch frame via a turning sheave to a small horn cleat mounted within the coaming. This permits infinite adjustment within the strut's range, and prevents you being brained by the mechanism if you get thrown. Also extremely simple and maintenance free.


A winner all around :-)

TP

[sailor_ed]

It should be noted that some gas springs are available in 316 SS.

[Dougtiff]

Look at " Port townsend foundry", they have a selection of Skylite opening fittings, all Bronze, beautiful stuff.

[Var Korall]

Nice stuff Dougtiff! Good job!

[thruska]

Originally Posted by Rowglide

I appreciate the simplicity of gas cylinders but they don't appeal to me aesthetically.

Sometimes you need to let function trump asthetics... no ?
Antigue them spray with rustoleum hammered look paint copper or bronze.

[redhead]

Originally Posted by Dougtiff

Look at " Port townsend foundry", they have a selection of Skylite opening fittings, all Bronze, beautiful stuff.

When we stopped by to see what they had last year, they took us on a tour of the foundry, answered all our questions and generally made us feel as though our business would be a pleasure.

Their work is impeccable, done in the traditional ways, and they are delightful people. So glad you brought them up!

[Rowglide]

That Port Townsend hardware is amazing!!!
Unfortunately I cannot bankroll hardware quite that nice. Besides, I'd really have to up my varnishing skills too!!!

[bailsout]

I don’t think you can beat the notched teak pieces for simplicity or aesthetics. I will experiment with it on my forehatch.... very Herreshoff solution and very apropos for my Herreshoff.
Another possibility are folding springs but allows only for full open or full closed and if there are two for each door might require too many hands.

[Rowglide]

A solution (I hope)
I picked up these "conservatory window cranks" or screwjacks in the UK.

50.00GBP!!! for the pair. (about $65.00 US)

They are double screwed so the total lift is about 12" and there is a quick relaes pin at the top to allow easy disconnection for opening further.
They are chrome plated brass, not bronze but for that price. also available in polished brass and "antique brass" finishes.
They were also available with permanently mounted crank handles but they stick down into my headspace. I'll shape up a nice crank for them out of aluminum or stainless rod (whichever I find lying around first).

[stainless guy]

I build a lot of products for customers using gas struts they do have their place and can work well for holding open aswell as closed but a marine environment is not a great place for them

The screw opener is what I was going to suggest and is a fairly simple thing to make for a competant metalworker.
If you need more opening room than that offers a scissor opening mechanism may be a better choice

Use ACME thread profile and brass or bronze for one half and s/s for the other to avoid galling