Hunter Horizon draught

Qi have had my Hunter Horizon 23 bilge keel yacht for about eight years and have always wondered about the stated draught of 3ft 1in. i measured the draught and on my boat it is around 3ft 8in.

i calculated that 1in difference in draught would equate to around 400lb to 500lb being added.

The boat has a 8hp 4-stroke engine plus a spare 4hp 2-stroke for safety and we carry around 60lt of water which would add to the boat weight plus all the normal food, meths for cooking and bedding along with anchor and two large bags of clothing.

i sail on the Broads which is brackish but mostly fresh water. How much difference does salt water versus fresh water make?

Can you explain? David Beeken, Norfolk Andrew Blyth responds:

I agree with your estimate that weight required to increase the draught by 1in is about 500lb in salt water. Fresh water is less dense than salt but the effect on small craft is very slight (only 2.5%) so in your case this is negligible.

Unfortunately we don’t know to what loading condition the quoted displacement of 2,745lb refers. The quoted ‘max draught’ of 3ft 1in should match this weight but it doesn’t always, so it should relate to a fully-loaded boat.

Very roughly we are looking for a discrepancy in weight of around 3,500lb – more than doubling the displacement!!!

I strongly suspect the quoted draught relates to an unloaded boat, as the quoted weight of the boat less ballast is only 1,310lb, yet the weight of four crew plus their kit alone must be over 700lb. The weight of the outboards, fuel and water you mention must exceed 200lb. But even if the total payload is well over 1,000lb, this still doesn’t explain all the difference in draught.

GRP immersed in water for a prolonged period of time does absorb considerable quantities of water, and your boat could be nearly 30 years old, and this is almost certainly a major contributory factor. Plus there is always ‘weight growth’ due to modifications, layers of paint, extra spares carried etc.

Is your boat overloaded? It sounds like it could be, but unless you can contact the designer I think we’ll probably never know (assuming your boat predates the RCD).