Early model F4 folding cockpit bench seat hinge info required.

[dellquay13]

Hi,
Can anyone with an F4 with the original 'lift and fold back' cockpit benches, with the three part aluminium hinges, help with some measurements please? I need to know the size of the back hinge square channel section where it fixes to the cockpit side, roughly 30mm x 100mm from memory.
To be exact in case of different sizes or hinges, the hinge in question is the port side rear hinge, and the hinge is in three parts; cockpit side square channel section, seat base square channel section and connecting arm.
Thanks in advance.
Chris

[dellquay13]

Hi,

The sketch shows the type of hinge, and which dimensions I am looking for. This hinge type was probably used on many models with folding cockpit bench seats, certainly in the mid 80's, and most likely for quite a period before and after, being made from easily sourced aluminium stock that Shetland could simply fabricate for themselves.

Thanks in advance

Chris

[daveflack]

Hi, looks the same as fitted to my Black Hawk.Is it something that new "Shetland supplier " as per the advert on our web site might have ? cheers Magic

[dellquay13]

Hi Magic,

Quayline may have bought the moulds, but I can't imagine them having the details of the hardware fitout of boats made forty years ago, especially when I don't want to buy anything.
I just need the dimensions shown, to fabricate something, but my boat is moored nearly 300miles from my home, so I can't just pop over to it and look, and was hoping that a member with easy access to their boat could help.

Thanks,

Chris

[daveflack]

Hi again,if I'm at my boat this weekend I'll take some measurements & check all 3 in case there are differences cheers Magic

[Franknstein]

I bought some stainless ones on Amazon, which I am hoping will do this job. I have them and they look pretty good and sturdy.
Link below:

I bought these ones:
https://www.amazon.co.uk/MagiDeal-Polis ... inge+shelf

more available:
https://www.amazon.co.uk/SeaLux-Stainle ... hinge+seat

Search: stainless folding hinge shelf
on Amazon, loads come up.
Hope this is helpful.

[daveflack]

Hi dellquay, I said if i could i would well i did so i have.Dimensions you req' the 2 rails are 15/16 (ish) "C" section,with a wall thickness of 1/8" (3mm) one piece 61/2" long & the other 3" long,the short unit goes on the hull side. The link arm is 1/2" sq solid section 61/4" long.pivot holes are 8mm in from open side of c section, using your sketch,the hole is 8mm from the end edge & 8mm from the openside edge.On the long (top rail) the hole is again 8mm from open edge 31/2" from the end edge.The link arm has a hole either end 1/2" in from end face.the mounting holes on the shorter piece are 11/4" & 21/2" from opposite end of section to the link hole. The longer piece (the bit that fits to the seat base) has a hole 1/2" in from either end.Again using your sketch,the link arm mount hole on the upright rail is at the bottom,the link arm hole for the top rail is nearest the right hand end (furthest away from the imaginary corner). my units are still fitted so I can't give you a size for any of the holes for the fixing screws & rivets etc but i would suggest they are probably 3/16" (5mm).Hope this helps,& apologies for my lack computer savvie otherwise id have posted a drawing/picture cheers Magic Flack

[daveflack]

hello again ,not sure if those suggested stainless units would work because of the "fixed" single pivot position

[dellquay13]

Hi Magic,

Thanks for the comprehensive measurements. The hinges are in good order, but I need to fit an enlarged backplate to one as the screw holes on the wooden batten on the hull have shredded from the strain of climbing in and out in that stern quarter for the last 20 years, and I want the spread the load a little. I am fitting the hinge to an aluminium plate, and needed the length of the section that screws to the hull to cut the plate before heading for the boat. The drilling I can do easily on board.
Cheers,

Chris

[Franknstein]

Hi Daveflack
I've translated your description of the seat hinges as best I could. Many thanks for the details. As you mentioned those hinges I posted won't work for reasons stated, the seat would hit the deck.

Would you mind seeing if I've done the drawing correctly please? I've assumed when you say holes are a certain distance from a face, you measured to the centre of the hole, and also I've assumed the holes at a size of 5mm diameter. The drawing is to scale.

I'm also quite interested in the arrangement of the lower legs that support the seat base, my boat was bare so I've got no idea really how they were arranged, as the seat hinge in this design wouldn't provide any natural support for the seat... what about the rear part of the seat base where it meets the side of the hull, does it sit on the fibreglassed ledge? I've also noticed in the drawing that the corners of the link arms will hit the inside of the c-channel, is this intentional to provide a kind of 'locked' state in the seat hinge arrangement or an error in the drawing?

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