Does baseplate thickness matter?
Q I have been asked by my builder if I want to go for 12 mm instead of 10mm for my baseplate. Will this make a big enough difference to make it cost-effective? The steel people have apparently made me an offer at a good price.
BILLY BOYLE, via the CB website
A TONY REPLIES… Much depends upon the quality of the steel and other factors. A 12mm baseplate will be heavier than a 10mm one so the hull will need less ballast. This will allow the builder to fit a lower floor (for greater headroom).
Steel comes in a number of grades and some probably come with no grade at all. With graded steel there is a far better chance of the quality being consistent. A choice between 10mm graded steel suitable for hull work versus 12mm ungraded steel might make the 10mm a better and possibly longer lived option. You will need to research and discuss steel grades to be sure.
Springer boats were originally built with the equivalent of 4mm or 5mm base and many are still in use maybe 40 to 50 years later. Dutch motor cruisers are often built from 6mm steel, while 6mm or 8mm baseplates have been common in the past and are still in use today. With (say) 10mm base, 6mm hull sides and 4mm cabin sides and roof, it is almost certain the sides will require plating long before the base.
If the steel quality is the same, 10mm is perfectly adequate but 12mm is nice to have, especially if you are tall. As so many people think thickness is all that matters, using 12mm will probably give you an advantage when it is time to sell.