>>> using a foot pump it is hard unless you have a bit of weight. My friend at 11 stone has no chance of inflating the keel, I have to use all my weight and am a big unit. You may need a different pump.
The best LP footpumps I've ever used are the old Avon mahogany and hypalon ones... lots of air per stroke and get to pressure easily.
I've needed ones with an HP facility for some years now though and last year bought a new Bravo 9. This has proved to be one of the best modern pumps... so good I rarely bothered with the noise of my Bravo elec pump on this year's holiday. The Bravo 9 has a removable plug you pop out as the pump starts to resist and that "gears" down the strokes so they give less air volume but its 10x easier.