Inflatable dinghy bottom boards

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doug748

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I want to make a set of lightweight boards for the rear of an Avon Redcrest. The standard ones are big lumps of ply and difficult to stow on a small boat.
The new ones will be roughly 3ft square and I will hinge them in the middle either with fabric, or rope lashings.

What is the lightest ply that I can get away with, I guess 3/8th?
Has anyone else had any genius ideas for alternative materials to use....thanks.
 
doug748 said:
I want to make a set of lightweight boards for the rear of an Avon Redcrest. The standard ones are big lumps of ply and difficult to stow on a small boat.
The new ones will be roughly 3ft square and I will hinge them in the middle either with fabric, or rope lashings.

What is the lightest ply that I can get away with, I guess 3/8th?
Has anyone else had any genius ideas for alternative materials to use....thanks.
Click to expand...

I wonder if your dinghy is quite old? I had Avon Redcrests which had heavy, unwieldy 3/8" plywood floor panels. I think that originally they fitted into alloy sections, and were quite difficult to fit. As the dinghy had to be deflated and stripped to go into the back of the car after every trip, it was a pain. My present (newer) Redcrest has four 6" x 1/2" wooden planks, which fit into slots in a fabric base, and simply roll up with the dinghy. This is much simpler and better.

If you need to stay with the original design, then yes, they are made out of 3/8" ply, and hinged using material which looks suspiciously like car seat belt material.
 
Thanks for the responses.

Yes Norman it is quite old. I have the original floors and they do have to be fitted when the dinghy is deflated, as you say a pain, particularly on deck.
I have this idea of making the boards just as far as the seat and splitting them lengthwise. I am not aiming for perfection just to take a little of the wobble out of getting onboard. 1/4 in ply might do it - or might split first time out :-(
 
Doug, I have just made a pair of boards for our Avon Redcrest using ordinary cheap plywood from Wickes. Supposed to be 12mm it actually measures at 10.8mm. I measured the maximum width I thought I could get away with which is about 32". However, then bought a pair of old boards and they are 34". Whilst they look like Redcrest boards, they could be off anything.

The original plan was to use 2 U shaped aluminium channel pieces back to back to join the boards length ways, but the car seat belt idea sounds better. The only thing I have forgotten is the 4 round holes for the inflatable seat toggles, so more drilling required.

Pete
 
When the slats started to break on our Bombard, we just got rid of them.
Been using it about 10 years like that, no problem at rowing and 2HP/3.5HP speeds.
 
lw395 said:
When the slats started to break on our Bombard, we just got rid of them.
Been using it about 10 years like that, no problem at rowing and 2HP/3.5HP speeds.
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The slats on our Redcrest broke, which was no surprise, as Avon had stupidly used plywood. Plywood for the original design of their full area floorboards was fine, but for relatively narrow slats, was bound to fail. I replaced them with some 1/2" sarking, left over from my garage roof. Excellent. I hated using the dinghy without any floorboards.
 
Doug, the Avon boards I have a 18" by 34.5". They were difficult enough to fit at home, would be a very difficult on the bow of a yacht. So I am going ahead with the home made boards fitting a strip so they are 33" wide with a series of plastic hinges.

My trusty helper wanted a dinghy ride because that means walkies :rolleyes:

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Pete7 said:
Doug, the Avon boards I have a 18" by 34.5". They were difficult enough to fit at home, would be a very difficult on the bow of a yacht. So I am going ahead with the home made boards fitting a strip so they are 33" wide with a series of plastic hinges.

My trusty helper wanted a dinghy ride because that means walkies :rolleyes:

.....
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Great...... I think there is a seadog section in PBO.

Your photos show just the sort of thing I was after, thanks for posting those. Split that way they are perfect for stowing in a single quarter berth. Did you buy the plastic sheet? It looks ideal.
 
I did this for a Redcrest, I used B&Q plywood, 6mm, one single piece, a sort of oblong shape, with the corners cut off aft and a taper at the bow end, but truncated, not right into the pointy end. Once coat of thinned pre-kote, one neat coat, 2 coats Danboline.

It transformed the dinghy from a wobbly worry to a tremendous tender. 6mm seemed perfectly strong enough and I'm 18 stone, was still in good shape after several seasons.

Maybe not so easy to store a single board, but I reckon the best solution, 6mm helped with it being light.
 
doug748 said:
Great...... I think there is a seadog section in PBO.

Your photos show just the sort of thing I was after, thanks for posting those. Split that way they are perfect for stowing in a single quarter berth. Did you buy the plastic sheet? It looks ideal.
Click to expand...

Doug, the white sheets are Wickes 12mm (actually 10.8mm) plywood with a several coats of Dulux. They are heavier than the Avon boards but being able to fold them will as you say make storing them easy on or under a berth. I have just ordered 3 of these to hinge them: https://www.ebay.co.uk/itm/Polymide...ade-Industrial-Door-Locker-Hatch/401630227123.

With the hinges on the underside and a left over piece of ply 100mm wide over the top of the join screwed to one side only, it should stop the boards lifting in use. Well that's the hope anyway.

Pete
 
In case anyone is following this, here is the nearly finished article.

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It may well be that Pete's nylon hinges would be a easier and stronger solution but the webbing seems ok, time will tell.

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I will have to do something with those sharp bolt tails or it will stow badly.
 
They look great, Doug. :encouragement:

I picked up a cheap old Redcrest last month for fun at the beach. I've tried it once and was acutely aware that a firmer floor will help.

But I'm surprised that people are suggesting thicker ply than 6mm may be necessary. Considering sailing dinghy decks are often only 6mm, and that the Avon's hypalon floor doesn't strictly speaking need any reinforcement, and considering that spreading one's weight across a broad area of generally supportive floor will reduce potentially damaging localised pressure on the ply, isn't 6mm ample?

Burgundyben's description doesn't surprise me.
 
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While we're here, what's the best puncture repair fabric and glue for elderly Avons? I've no doubt Avon produces a kit for more than I paid for the Redcrest; for my money I'm pretty sure a good two-part adhesive and non-branded hypalon patches will suffice, but there are so many answers on Google...

...one of them boasted its quality, then stated that for a lasting repair, its single-part glue was wholly unsuitable. :rolleyes:
 
dancrane said:
But I'm surprised that people are suggesting thicker ply than 6mm may be necessary. Considering sailing dinghy decks are often only 6mm, and that the Avon's hypalon floor doesn't strictly speaking need any reinforcement, and considering that spreading one's weight across a broad area of generally supportive floor will reduce potentially damaging localised pressure on the ply, isn't 6mm ample?

Burgundyben's description doesn't surprise me.
Click to expand...

Yep! Absolutamundo correct. 6mm is plenty.
 
That looks a great job - the only thing I can think of that needs caution is if someone stands in it when the dinghy is pulled up on any stones care would be needed not to make a hole. Without the deck you may feel the stone(s) under your feet. But it looks very professional and easy to store - great job! Might even go and buy a piece of ply tomorrow!!:)
 
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dancrane said:
While we're here, what's the best puncture repair fabric and glue for elderly Avons? I've no doubt Avon produces a kit for more than I paid for the Redcrest; for my money I'm pretty sure a good two-part adhesive and non-branded hypalon patches will suffice, but there are so many answers on Google...

...one of them boasted its quality, then stated that for a lasting repair, its single-part glue was wholly unsuitable. :rolleyes:
Click to expand...

I had mine repaired last year - not sure what was used but I do remember it was important to have the correct glue and patch. If there is a large hole a patch can be applied on both the inner and outer surface.
 
That looks like the right stuff, thanks Doug...although, I wonder how many parts that 2-part glue consists of. Looks like three or four!

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If you have a branch of Buck and Hickman close by, you can buy Bostik 2402 which is what Avon used as far as I know. A 250ml tin is about £12. They also sell Duralac.
The Bostik product, and probably the Polymarine etc ones have an annoyingly short shelf life so watch the use by dates and do as many jobs as possible in one go. Guess how I know that.....
 
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