steaminafglasshull

Steam power in a fibreglass hull ?

But once you've taken the plunge and made a sizeable investment in one of the modern ready to run and relatively user friendly steam plants available today, something around a thousand pounds in the upper reaches of the market, and rather more if you add a few of the available accessories like water pumps and automatic burner controls, just what kind of model are you going to put it in?

A ready made GRP hull of some suitable steam powered prototype is probably the most obvious solution to the problem, certainly the simplest and speediest route to the water in most cases, but some of the modellers who contact me still seem to have niggling doubts about the advisability of mixing steam plants and plastic hulls.

How long would it take you to make a hull like this steam yacht the good old fashioned way from wood? Plenty of room inside, with no ribs and formers to get in the way.

Yes, I know that almost every issue of every model boating magazine, and this website too of course, contains pictures of successful steam powered GRP hulled models, but despite this, the combination really does worry a significant number of people.

The usual reason is that they have read somewhere that GRP or Glass Reinforced Plastic, fibreglass as it's more commonly known, is made from highly flammable materials, which is of course perfectly true. This makes them think that the finished product in this case a moulded model boat hull, must also be flammable, but really nothing could be further from the truth. With proper planning and a few sensible precautions, there really is very little to get anxious about.

In the final analysis, should major disaster strike, it's quite true that a model boat built on a GRP hull is capable of making a merry blaze, probably sufficient to roast chestnuts over in fact, but then so will a model boat made from most other kinds of material particularly if spilled fuel or leaking gas is involved, as is often the case with steam-related mishaps.

The polyester resins that are combined with glass fibres to produce GRP mouldings are organic compounds. They are composed mainly of hydrogen, oxygen and carbon atoms, so like most organic materials they will burn, but what's the most likely alternative to a GRP hull? Yes that's right, a wooden one, and wood is also an organic compound. Chemically in fact it isn't all that much different from GRP, just a million or so years younger, and wood will catch fire in the first place much more easily than any fibreglass hull.

Wood also has minus factors that GRP does not. In most cases, wood hulls have a fair amount of internal structure, bulkheads and formers and the like, and this can be a problem when it comes to the installation of a bulky steam plant. With a GRP hull this internal impedimenta is much reduced, something that eases installation and access considerably.

This shows one of the advantages of a fibreglass hull, plenty of space with no internal structure to get in the way.

Also, as all wood is absorbent to some extent, it will soak up spilled flammable fluids like oil or methylated spirits. This is obviously something that adds significantly to the fire risks, and the problem is greatest where softer woods like balsa, obechi or spruce are involved, as they are in the majority of models.

Naturally you'd try to cover every scrap of bare wood that's visible, or of course accessible, with some sort of coating. But this isn't going to provide total protection for ever and a day, and many such coating materials, paint and varnish for example, are themselves flammable in some degree.

GRP on the other hand doesn't need to be painted over at all, and it can only soak up fluids in very localised areas after the moulding itself has been quite seriously impact-damaged or abraded. But it's the heat that's the real worry though isn't it? Steam-powered models all have a lovely hot oil and metal smell, and you can burn your fingers on most of the mechanical bits as easily as anything. That and the fact that they sail around with a gas or meths fed flame burning deep in the heart of that precious model, so aren't we right to be at least a little concerned?

Well no, not really. Almost any model, no matter what the hull and other parts are made from, will contain significant amounts of flammable material, wood, plastics and paint to name just three. In the event of a serious fire these other ignitable materials, usually in the shape of decking and superstructure, would be well on their way to turning into ashes long before things got hot enough to cause the GRP hull to join in, and by this time there wouldn't be much left worth salvaging in any event.

So as I said earlier, provided you take sensible precautions at the outset when installing steam plants and every time you operate them, the risk of fire or other heat damage should be minimal. In any case, present day steam plants are far easier and safer to operate than some of the slightly suspect home-made creations of days gone by.