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An idea for new superstructure .....?


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Hi all :)

 

Now then, sat here pondering like i do. I have a boat ( customers ) that is in need of the ply/GRP super structure being replaced.  I have an idea that i have not thgought about fully as just thought of it but it works in other structures so why not a NB. ?

 

Idea, is instead of timber and GRP ( yes steel which i am pricing up as trying to help keep cost down ) then in one go this will insulate and build in one the superstructure from PIR foam sheets and laminate it instead of ply GRP.

 

Thoughts :) 

 

Cpatin Faffer

 

( Waynes Boat Works )

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If I have this right, you have a steel hull with a superstructure that needs renewing.  You think foam sheet as the core in some form of laminate might slice the croissant.

My view: It could.  The hard part will be getting a decent exterior and interior finish.  Raw chopped strand mat does not cut it, and even fine woven rovings are not much better.   Fill and sand is bloody time consuming. Fire resistance needs to be thought about, so affects your choice of resin. Then you need to think about fixing things to the laminate: everything from bulkheads, via lights, to shelves.  After that pipe routes, cable routrs etc.  Not hard, just a lot of planning.

 

Can your client afford your time to do that?

N

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13 hours ago, BEngo said:

If I have this right, you have a steel hull with a superstructure that needs renewing.  You think foam sheet as the core in some form of laminate might slice the croissant.

My view: It could.  The hard part will be getting a decent exterior and interior finish.  Raw chopped strand mat does not cut it, and even fine woven rovings are not much better.   Fill and sand is bloody time consuming. Fire resistance needs to be thought about, so affects your choice of resin. Then you need to think about fixing things to the laminate: everything from bulkheads, via lights, to shelves.  After that pipe routes, cable routrs etc.  Not hard, just a lot of planning.

 

Can your client afford your time to do that?

N

 

Oh yes its a lot of work, but in the end the outer skin will be much the same as if i replaced in ply and then laminated to get a polished finish. 

There would be a frame work of  2x2 treated timber to mount the ply lining for the interior.  and end of the day its a complete new build so all need a lot of planning. 

At the end of the day it could be cheaper and better to replace will steel. I havnt priced up steel sheet for some time. 

 

 

13 hours ago, WotEver said:

I can't see why not.  It'd be nice and light too.

So more ballast needed, well thinking, not great deal more as the only part missing is the ply top. about 26kg per 8x4 18mm sheet.....so, oh i will work that out if needed in time lol. 

 

12 hours ago, rasputin said:

The fiberglass foam sandwich that refrigerated vans are made from looks like a good building material to me but I have never been able to find any to buy

 

 

Like this company 

 

https://www.scomp.co.uk/grp-product-range/grp-sandwich-panels/

 

 

I could make my own sandwich sheets but tha will depend on time and cost, but then it will have a smooth side and then joined.

 

 

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23 minutes ago, WotEver said:

I wonder what the maximum length they can fabricate is? Be great if you could get one piece for the entire side :)

From a quick look they do a max of i think 3.5m, although when i used to deliver to a fridge van companies they had sheets a dam site bigger for the whole wagon side. worth looking into they :)

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22 minutes ago, cuthound said:

Will the foam/GRP sandwich be strong enough to walk on?

 

The roof is a working deck on a narrowboat.

Much the same as a cabin cruiser with single skin.  Some you can some you cant. In true sandwich construction ( laminated both sides ) though there is  more strength in it. And as the roof is often curved on a NB then then that adds strength and ona curved roof you can laminate one side and still keep strength. and to add more, even if flat roofed then more laminations will do the job. For this curved roof i would go three lam`s of 450grm. If a flat roof maybe three 600grm that would give a thickness of around 5.5mm. There will be the frame timbers inside also.

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A steel top doesn't need much framing as it such a strong material but I think that anything else will need many hours of work to make it strong. As Cuthound says the roof needs to be strong and people sometimes  jump down onto the roof from locksides etc, if they are young and foolish.

 It is an interesting idea though, presumably there is a small 'upstand' in steel that the old top bolted to, might be awkward to fix a sandwich material to as you would need to be careful of the raw edge being constantly wet and a line of bolts might crack the stuff. I am a poor welder but OK with wood  and I have fitted a timber top on a boat with a steel upstand and it was successful.  I used oil tempered hardboard as a cladding but nowadays I would use some sort of acrylic sheet and as for the roof ....... dunno, I used canvas and paint on thick T&G and ply but that is a lot of labour and not brilliant for insulation.

Edited by Bee
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4 minutes ago, Bee said:

A steel top doesn't need much framing as it such a strong material but I think that anything else will need many hours of work to make it strong. As Cuthound says the roof needs to be strong and people sometimes  jump down onto the roof from locksides etc, if they are young and foolish.

I priced up steel in 3mm and it was around £2k, i am gong to put that to her and see what she wants to do. few ways to go with it. Its best as we know but down to the customer. Thing is there i can weld but never built a steel NB. I could tack it all up in place and get a qualified welder in or swat up more with my welding.. Only thing i will have to watch is distortion really. 

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I think I mentioned polyurethane foam and fibreglass construction as used in homebuilt aircraft when you were talking about stretching your Norman.

The foam is easily sculpted to shape and covered in fibreglass and gelcoat,then power sanded to a finish.

A point to watch though ,steel hulls with wood or fibreglass tops will leak after a time due to different rates of expansion.

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11 hours ago, W+T said:

I priced up steel in 3mm and it was around £2k, i am gong to put that to her and see what she wants to do. few ways to go with it. Its best as we know but down to the customer. Thing is there i can weld but never built a steel NB. I could tack it all up in place and get a qualified welder in or swat up more with my welding.. Only thing i will have to watch is distortion really. 

I know someone who did that on an old boat, he said it was a nightmare  more weight up top and more weight overall. I am not sure if he was a member here

 

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8 hours ago, David Mack said:

Is this for the person that posted a few weeks ago wanting her late grandad's boat sorting out? If so it looks like an awful lot of work to be done. Is the sentimental value really worth spending that much money?

 

It is yes.

 

46 minutes ago, ditchcrawler said:

I know someone who did that on an old boat, he said it was a nightmare  more weight up top and more weight overall. I am not sure if he was a member here

 

 

It may well need a shit load of weight at the bottom if the hull is 2mm thick lol.

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