sinking feeling !!

we've recently upgraded to a gp 1200 , but still use our 1100 triple as its been such a good machine.
We were out on the 1200 and the waveraider
But the other day we were having a great time jumping and splashing around then all of a sudden the waveraider started loosing power. we were about 5 miles from the slipway and limped back at about 5mph.
I noticed i seemed to be getting lower in the water.
After an hour we got back and recovered the craft.
I took the drain plugs out and what seemed to be gallons of water came out.
I noticed the visibility spout had come off but the bilge pump did appear to be working.
would the visibility spout make any difference to getting water out ..... or has anyone else experienced this ???
thanx
Stitch