Got this Today from Charles Broughton, Designer and Builder of the Pilot boats.
It's much the same as DiverDave's link.
----------------------------------------------------------------
Jim,
Looks like you have Tiddler balanced just right, great photo!
With regards to your discussion on maximum towing weights for trailers see the following link:
http://www.ntta.co.uk/law/law/identification_plates.aspx
This states that for unbraked trailers - max. 750kg gross trailer weight or half the towing vehicle's kerb weight - whichever is less. Kerb weight is the car weight including fuel, oil, etc. and can include the driver within the EU. So check the kerb weight of the tow vehicle and half it and then check the manufacturers maximum stated unbraked towing weight and use the lowest value as maximum unbraked towing weight.
The Indespension trailer for the Pilot4 weighs in at 135kg, add to this the boat only mass of 290kg, then add engine, fuel, anchor, battery, etc. to give your final towing weight.
Also check the following link for lots more information on trailers and towing:
http://www.ntta.co.uk/law/
Hope this helps,
Charlie
--------------------------------------------------------
Jim