Quote: "Could you explain what makes that massive difference in maintenence between 30 and 40 feet boat? "
Sure, but do understand that boats are riven with complexities and there are huge variations in maintenance
requirements not only between different marques of the same size, but also between individual boats of the same marque and size. So any discussion like this can only serve as a departure point for developing an understanding of, and a "feel for", these things. Some smidgen of familiarity with the principles of Cost Accounting will also help :-)
As I'm sure you know, displacement is a just a different name for weight. We needn't go into the matter of flotation here. Just note that if a boat has a displacement of say 9K lbs (as TP has) then she displaces 9K lbs of water
and weighs 9K lbs. Now imagine that her hull
were a solid object, rather than a hollow one, and made from a uniform material throughout. That material would have a certain price
per pound, say £1 per pound, and the "cost of materials" for the hull
would therefore be easily determinable as 9,000 x £1 = £9,000.
Now double the linear dimensions of this imaginary hull and the weight becomes 9,000 lbs x 2 x 2 x 2 = 9,000 lbs x 8 = 72,000 lbs and in consequence the cost of materials becomes not £9,000 but £72,000.
While mathematically correct, this explanation is obviously a gross over-simplification, because a boat is an agglomeration of dozens upon dozens upon dozens of "systems" and individual parts
. As displacement increases, the forces that wind
and wave impose on the boat grow. The "gear" must therefore be sturdier and in consequence more weighty as the size of the boat increases. You can therefore go through the same logic for even something so simple as a rigging
screw. By the time you've done that for all the components of the boat, you'll find that increase in displacement is a reasonable (although not quite accurate) proxy for increase in maintenance cost. Empirical observation bears that out.
In a twenty seven foot, two ton boat you do not need a capstan. In a forty foot, 10 ton boat you do. TP's capstan, a bit of a wimp really, would cost about 1,000 quid (taxes in) to replace if it needed it. In a five tonner like TP, for the kind of sailing I do, in the water
where I sail, I do not, even at my advanced age, NEED a capstan. In a ten tonner, say a 36 footer, I would!
The switches that operate the capstan are toys. But that's what you get for the money. When they pack it in, as they will, the cost to buy them is not ferocious, so if you know what you are doing with electrics, you can replace them yourself. If you can't do that, marine
electricians around here charge 60 quid an hour.
And so it goes.
I transfer Can$1,000 (= £600) a month in the "TP account" which is kept separate from all my other financial affairs. Obviously the balance fluctuates, but over the long haul, major expenses can be covered by the balance just like the ongoing fixed monthly expenses like moorage and insurance
are. Such a separate account is, with wonderful irony, called a "sinking fund" :-)!
When you buy an older 27 foot, two-ton boat, you may get by with an outboard motor
slung on the transom. Particularly if you day-sail or weekend-sail in benign waters. In a 30 foot, five ton boat, that gets dodgy particularly in waters such as the Salish Sea with tidal streams that often run eight knots. In a bigger boat than that, an inboard diesel
becomes, IMO, mandatory. A well treated diesel
lasts forever and a day. but if you do have to change it, a good diesel like a Beta in a five tonner will cost you about 9 thousand quid to replace. Bigger boats require commensurately bigger engines.
In these waters we count on installing 4hp per ton displacement, so TP would require a 20HP machine, a 10 tonner like a Pacific Seacraft
40, say, would require 40HP.
As for sails
, when you have to replace them, as you may have to do every ten years or so depending on where you sail and how hard you sail, they can be within reach cost-wise, or they can set you back a king's ransom. Because the previous owner of TP, being obviously naïve about sailing and having ODed on glossy mags, fitted such a pedestrian cruising boat with roller furling
sails (the main being mast-furling, no less!!), I need to budget as a minimum the equivalent 6,000 quid to replace a 200 Square Foot main and a commensurate 135% genoa!
So let's loop back to the top of this missive: The numbers I have given you are NOT DETERMINABLE WITH PRECISION! Neither is the time they will smack you in the face. But if you don't have the brass behind you when that happens, you can find yourself in a very awkward spot. And so can your boat.
As I said, Empirical observation supports using displacement as a proxy for establishing cost estimates for yachts.
All the best