hull strengthening membrane?

[David MeierParticipant @davidmeier28154]

Hi. I am building my first scratch built boat, a tenth scale of a 7 meter Italian fishing trawler. It is balsa planks on ply frames. I have had to use a fair bit of filler over the planks in places to get the hull form right (this is my first attempt remember). The filler I chose for its ease of sanding and similar hardness to balsa is PAL contract filler, interior & exterior.

I would like to coat the hull with a strengthening membrane but am put off at the price of fibreglass cloth and resin. I have heard of people using tissue and dope (I assume it is paper tissue). Can anyone tell me of a low cost method that will put a bit more strength and durability into my hull? I would apreciate any helpful tips on how to apply the coating as well.

Regards.

David. 

[Bob Abell 2Participant @bobabell2]

Hello David

I would recommend you cover the balsa with 300lb cartridge paper plates of scale proportions using PVA…………….. with Fibre glass resin on the inside

Have a look at my gallery……….Jeanie Deans at war……….that`s what I prefer!

Bob

[David MeierParticipant @davidmeier28154]

Thanks for the help Bob.

David.

[60wattParticipant @60watt]

Hi David.

I’ve used epoxy with fine woven glass cloth to give a near invisible tough layer.It does away with a lot of filling but it showed every flaw. Unlike a coat of paint, there is no going back after coating with glass.

Glass tissue soaked up a lot of resin and gave a very rough finish – no good.

I would advise you to go ahead and buy fine weave/epoxy and do experiments beforehand.You would probably use it on every model thereafter.

Tom

[David MeierParticipant @davidmeier28154]

Thanks Tom.

Where do you source the fine weave cloth? and do you have an ounce rating that I should specify? When I have looked in hardware stores and auto shops they only have a heavy grade of cloth or chopped strand matt.

David.

[60wattParticipant @60watt]

The only place I have seen it was my local model shop which stocked everything for model planes.It came as a Ripmax kit with a couple of metres of very fine translucent silk like cloth and 3:1 mix 24 hour epoxy.I think the wholesaler description was a "skin preparation" kit. An aeroplane forum would locate some.

A square yard left weighs 12 gram – on a par with glass tissue

I have used paper tissue with dope as well but it does not even begin to compare with possible finish or strength. I repeat the "experiment first"

Tom

[60wattParticipant @60watt]

See page six

It goes clear on wetting and can be re-laminated when tacky.

Tom

[David MeierParticipant @davidmeier28154]

Thanks Tom.

That looks like the way to go. I supose it is silly to skimp on this and compromise the model.

The PDF link is a good resource.

cheers.

David. 

[60wattParticipant @60watt]

For scale effects I’d stick with Bob’s idea.At least you can start again if you din’t like the results.

Keep trying with the radio.I found faults came into the obvious and simple-to-fix category.

Tom

[David MeierParticipant @davidmeier28154]

A smooth hull finish is what I am after so I will go with the fine glass cloth. As for the transmitter; not my strong point. I have looked closely with a magnifier and nothing stands out. Thanks for your help at least I have learnt something through the exercise.

cheers.

David.

[TelstarParticipant @telstar]

Hi David     I covered a plank on frame 1meter hull by streaching material from a pair of tights over the hull and epoxy.  It gives a strong skin, that can be painted and finished as normal

Cheers Tom

[David MeierParticipant @davidmeier28154]

Hi Tom.

I Like that idea, the tights would stretch and conform to the compound curves of the hull which are especially tight around the transom. Also this sort of approach fits my budget better.

Am I  right in thinking that the material you used was nylon as used in stockings and pantyhose or do you mean a thicker material?

cheers’

David.

[Tony HadleyParticipant @tonyhadley]

Hi David,

The hull on my 1920’s replica vintage yacht was balsa planks covered with one leg from a pair of ladies tights. All as the method which Tom has suggested. I didn’t use any epoxy, just paint and varnish. Use fine denier tights as they wont take as much filler/paint/varnish to cover the weave.

Also flat areas can be covered in a very similar material, called knitted nylon (I obtained mine from a dance suppliers). Fine denier material is best.

Regards, Tony

[David MeierParticipant @davidmeier28154]

Thank’s for the extra info Tony. Your model looks superb, I will be very happy if mine finishes up to that standard.

Did you use paints that have a hardener with them or just turps based paint?

Cheers.

David.

[Tony HadleyParticipant @tonyhadley]

Hi David,

I used Revell aqua colour paints and Ecos varnish. Ecos is a domestic environmental water based varnish, and I have had no problems. I always use Ecos for all household diy painting as it doesn’t smell and upset SWMBO. Any domestic varnish and paints could be used, but I do find the water based/acrylic do keep the colour better. i.e the white does not yellow.This purely my personal preference, others will probably disagree.

The problem I have had is controlling this yacht, on the water. She has a mind of her own!

I am now building a Veron ‘Police Launch’ using the same method for covering the hull. i.e. balsa covered with tights. After covering I applied a couple of coats of varnish, finally trimming the tights off at deck level when the last coat was dry. The hull can be finished to your prefered choice.

Regards, Tony

[TelstarParticipant @telstar]

Hi David      As Tony says use fine denier ‘Nylons’ to give a fine finish, and light wieght.

Hi Tony  Its good to know other builders use this material

Happy modelling and a Merry Christmas Tom

[David MeierParticipant @davidmeier28154]

Hi Tony and Tom. Thanks for the very detailed and clear information. Useing acrylic enamel makes sense as I understand that acrylics dry from the base to the surface; whereas turps based enamels form a skin first and then the underneath hardens up.

Here are a couple of pictures of the trawler I am building. One of the first planks going on and the other at the stage I am at now with the model. Still a bit more sanding and filling to do before I put on the nylons.

[David MeierParticipant @davidmeier28154]

[Author]

Posts