Dory building with foampannels?

[hannes]

did some build a dory(eg Gloucester Dory) with foampannels? I found a thread of building the duckpunt, but the sidepannels of a dory are twisting more.

br hannes(vienna or greece)

[Chris Waite]

I don't know of anyone on the HBBR circuit, or elsewhere who has used foam panels, Hannes

Apart from the duck punt as you say.  I suppose you could heavily 'score' (partly cut though) solid foam to bend it then fill the gaps, before glass fibre-ing over; which is what I assume you're going to do?

I was considering installing some in my little raid dinghy in the sides of the cockpit as she tends to be very unstable and wallow (roll) heavily when swamped.  However, I've found a more convenient answer by lashing fenders into the chine area.  These can then be used as rollers for moving her about on the foreshore; they work very well as I accidentally found out -



Or they can even serve as fenders

3-in-1 equipment!

Chris W

[hannes]

I will try your “scoring“ hint

My idea is to use foam(10mm from floorisolation) instead of ply during the stitch&glue-process.

Why?

cheap, light and easy to get


br hannes

[Port-Na-Storm]

Hi Hannes,

What type of foam do you plan to use?

EPS Expanded Polystyrene, which is usually white and slightly crumbly, absorbs water unless you seal it. I think Cellotex is closed foam but it doesn't like to bend at all.

G

Sent from my Xperia by Sony smartphone

---- hannes [via UK HBBR Forum] wrote ----

I will try your “scoring“ hint

My idea is to use foam(10mm from floorisolation) instead of ply during the stitch&glue-process.

Why?

cheap, light and easy to get


br hannes

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[Timmo]

Foamed PVC Sheet is also worth considering. Potentially a good balance of water resistance, strength and flexibility, though it may be more costly than alternatives.

http://www.plasticstockist.com/Foamed-PVC-Sheet.aspx 

I've used it for a number of structures used in my wife's day nursery, can be glued using solvent cement designed for pvc or contact adhesive. Pretty robust stuff (though nothing survives small children for ever.)

Tim.

On 1 Mar 2019, at 08:27, Port-Na-Storm [via UK HBBR Forum] <[hidden email]> wrote:

Hi Hannes,

What type of foam do you plan to use?

EPS Expanded Polystyrene, which is usually white and slightly crumbly, absorbs water unless you seal it. I think Cellotex is closed foam but it doesn't like to bend at all.

G

Sent from my Xperia by Sony smartphone

---- hannes [via UK HBBR Forum] wrote ----

I will try your “scoring“ hint

My idea is to use foam(10mm from floorisolation) instead of ply during the stitch&glue-process.

Why?

cheap, light and easy to get


br hannes

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NAML

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[hannes]

I will use xps(pink, green, blue or yellow, not the white one)

[John P]

For the structure of a boat hull you probably should be using proper marine structural foam, not foam that is mainly intended to be used as thermal insulation.

As it happens I have recently started to do boat work using foam although my practical experience with using it is still rather limited.  So far I have been using a sheet of Corcell M80 but I will run out of that and will need to buy more foam very soon so I have made a spreadsheet comparing the cost and mechanical properties of three different types of structural foam - see attached.    I don't have up to date information for the cost of Corecell M80 so that price is missing from my spreadsheet.  I have an idea it is somewhat more expensive than Airex, I have asked for a quote from the UK distributor (Marineware).

Of the three types of foam I have compared on my spreadsheet there doesn't seem any huge difference between the mechanical properties.  The shear modulus is arguably the most important mechanical property if you want to make stiff light panels, although other properties may be important if you are looking for other requirements such as impact resistance.  The shear modulus is very similar for the three foam types.   However, there is quite a big difference in the price - the EasyCell75 foam from Easy Composites is £26.85 per m2 at 10mm thickness, compared with £61.40 per m2 for for Airex C70-90 at 10mm thickness.   If you buy 5 full sheets of Airex C70-90 this reduces to £53.81 per m2.   On the face of it the EasyCell75 is better value, but there may well be factors I am not aware of.