hi there Mike
not wanting to rain on your parade or put you off in any way - but judging by your questions - (model boating) - may be a very new hobby to your goodself - with totally new methods and ways of construction. I would strongly advise that you sought ought Tynemouth Model Boat Club or South Shields model boat club - have a good nosey around and ask all the questions. Although any forum members are brilliant at answering questions - you cannot beat a 1 : 1 where you are looking at something you wish to construct and also you will see other problem areas & have a person there advising of how to get over them. Hey, its a lot easier doing it that way than over a forum.
To give you an example - how are you going to construct a hull from fibre glass - build a 2 part mould first? Or, are you going to use a foam block system? where you create the shape of a hull from a block of foam and then cover that with fibre glass and over the fibre glass you put a filler/sand to shape the hull? There are other methods of building hulls using fibre glass and as has already been suggested there are several ways of stiffening hulls and building them lighter.
I have put a link on here http://www.modelboatmayhem.co.uk/forum/index.php/topic,33734.0.html this is of a hull of HMS Exeter. Although its at 1:96 scale; its dimensions are 72 inches long. So the beam to length ratio will be exactly the same as you wish to build at 1:48 scale.
aye
john
Hello John
Thanks very much for your comments and, yes you are quite right about me being new to model boating. The Heaton club is closest to me and I do intend to make contact with them. Actually, the reason I asked about the GRP thickness is that I am thinking of building a hull out of tinplate - as described here:
http://www.modelboats.co.uk/news/article/model-shipbuilding-in-steel/480and also described in the book "Scale Model Warships" by John Bowen and in old articles by Norman Ough that I have.
I have numerous years experience of hobby-working with metals and using soldering methods etc and this approach for making the hull (of what I hope will be a R-class destroyer) really appeals to me for a number of reasons. I have obtained the lines drawings, body plans, shell-expansion drawings etc which will be needed for this project. A complication is that the hull has a small degree of tumblehome, but that means the former will have to made in a cunning way.
I am asking about the GRP thickness because I have read that tinplate hulls are no heavier than GRP and I wanted to do some calculations to check this out for myself. As discussed in the thread on displacment, weight will be critical since I plan to install steam.
I have not seen any posts on this site concerning tinplate construction, so I guess that this method is not very common - I'll be interested to hear if that is the case.
Thanks for the link to your Exeter build - I must say that looks really impressive and certainly demonstrates well the need to seek advice and guidance locally.
Thanks again Mike