solutions for opening heavy teak butterfly hatches...

[Rowglide]

Our Hans Christian 43 has an enormous butterfly hatch over the saloon. What is not to love?
More teak to varnish, I know, I know
Terrific ventilation
Great Natural light down below
and most important, it provides a large enough access to pull and drop in the monster Perkins 4.236 fully assembled with all accesories and transmission installed.
Oh and this one doesn't leak (yet?)

But what I do not love is the weight and height to open them. Ours are built of massive 1-1/2" thick teak and have 1/2" safety glass in them. They also have a heavy stainless grating outside just to weigh them down some more. My wife cannot reach them unless standing on the table and then cannot manipulate the knobs while supporting the weight. I can just reach them when standing on the settee (I am 6'2) but they weigh a ton to open and have annoying knobs at each end that need to be loosened to open and then both tightened before letting the weight rest on them.

Does anyone have an improved "System for raising theirs? I have considered gas charged cylinders but they tend to go all or nothing and it is nice to vary the opening based on wind / rain / spray conditions. Not to mention they are about the opposite of "traditional" in appearance.

Let me see your systems and ideas

[Sulaire]

I go on deck and raise mine from the outside.

[Suijin]

I have old Lewmar super hatches on my boat and a couple of them won’t stay open by themselves any longer and the parts to renew the hinge mechanism is $50. I made a few teak sticks of varying widths with notches in them as a stopgap and like them so much I may never bother fixing them lol.

Would be easier than futzing with those slide and knob hinges you have.

[davil]

Great idea

[Bill O]

Always thought this was a really nice one we saw at a boat show, but too darn expensive. We then found a drawing similar to the Sparkman & Steshens crank.

[Suijin]

Originally Posted by Suijin

I have old Lewmar super hatches on my boat and a couple of them won’t stay open by themselves any longer and the parts to renew the hinge mechanism is $50. I made a few teak sticks of varying widths with notches in them as a stopgap and like them so much I may never bother fixing them lol.

Would be easier than futzing with those slide and knob hinges you have.

Just to be clear that should have read “lengths” not widths. They were fashioned from a piece of teak scrap from a boatyard and are about 1”x.75” and as long as needed. I shaped the ends to fit as securely and neatly as possible as props but in truth the weight of the hatch holds them in place.

Won’t aid actually opening them but a short pole with a rubber bumper on the end (a wooden cane essentially) would probably help.

[Rowglide]

Bill O!!!
That is EXACTLY what I am after. Might have to brush up on my brazing skills a bit but I think if I can't locate such a part, I could certainly build them.
Jim

[Sailshabby]

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.

[Cadence]

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

[redhead]

Originally Posted by Bill O

Always thought this was a really nice one we saw at a boat show, but too darn expensive. We then found a drawing similar to the Sparkman & Steshens crank.

I have been lusting after these for a year now but had never seen the drawings. I even talked to a foundry about making some up for us, but the cost was astronomical. Now if I take this schematic to them maybe they can quote a better price.

We have 3 butterfly hatches and currently I go up on deck to open them. P.I.T.A. Thanks for this!

[Var Korall]

I did a quick search online and found this one, among others: www.ironmongerydirect.co.uk/product/telescopic-skylight-screw-jack-opener-250mm-satin-chrome-361986 . They are in the UK but may have suggestions for you if you contact them. Also try skylight manufacturers.

[jhulmer]

I plan to use stainless gas springs like you see on a car hatchback.

Use a bathroom scale or fish weighing scale and get the weigh of one door.

You will have to do a little math to figure what the weight is at the point you will connect the gas spring, Length from the hinge to point of connection. Or you can just measure the weight at that point.

With that information you can size the gas spring. I would go about 20% to 30% higher to make sure it stays up. Or if you just want it to counterbalance the weight (make it lighter) use the measured weight. This is assuming that the gas spring will be more or a little less straight up when the hatch is open. There is mechanical advantage from the increased angle to the hinge that is increasing the weight otherwise, so you will have to increase the force size of the gas spring. A little grueling on figuring the angle for each position and doing a vector analysis to figure the force required or you can just WAG it and go with trial and error.

If you prefer a gas spring on both sides just split the weigh and size of the gas spring as above.

You can use your existing latches to set positions open.

https://www.defender.com/product.jsp...324&id=1333801

[Var Korall]

Here is another one, again, overseas. www.window-openers.com/traditional-window-openers/

[Rowglide]

OK so I have been puzzling on this and have a possible solution.
In the UK many homes have skylights and they have "Screwjacks" to open them. They are available with separate cranks with de-mountable rods (For really high windows) and with affixed cranks.
I haven't found any in cast bronze but they are available in brass and chrome plated brass. I am still trying to get exact dimension but the idea is right and they are not expensive ...21 pounds (about $21USD) plus shipping from UK.
Company I found is www.simplyscrewjacks.com

[Rowglide]

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