when i purchased 1705 i was trying to find all the leaks and went the wrong way about things and filled the hulls with "a little" bit of water in desperation! THEN i wrote to Tim Sheppard and got the right advice,I know pass this on to anyone who is serious about finding leaks and about not blowing their hull apart at the seams with to much air! You need a Hatch cover-pvc tube-spray bottle-12yo son & normally a tube of silafex. 1st drill a hole in the hatch cover and thread the pvc tube thru to create a valve (make sure you silicon around the tube to prevent leaks as well) screw your new hatch cover in and start blowing up the hull the same way you would a inflatable ball!! you will only need 2-5 breathes of air ) then put your finger over the pvc tube and ask your son to go around the hull and sparay a mixture of water with a drop of washing up detergent over any fittings and cracks & wait for the bubbles!!! I now have my boat so water tight i would be cocfidant to put my mobile in the hull for a couple of hours sailing without putting in a plastic bag!! when you get all the leaks sealed and blow a few breathes in the hullyou can actually put your finger over the pvc valve for a few minutes and let it off and it lets off that hissing noise as it holds all the air!! Thanks Tim for this advice i now do it every season only difference being my sons a year older!!