Searider is sooooooooooooo good
I have the pleasure of owning a 4 metre Searider with a 50 two stroke and its superb , loves the lumpy stuff and gives loads of confidence. Out of the few ribs I have owned up to 6 metres this is my favorite.
If you want to block off the flooding hull , best to fit a dinghy type circular removable hatch , which then gives you the option to simply remove it when you want it back as a flooding hull.
You would also have to block off front breather holes to completely seal it, howver blocking off the flooding hull you will miss out on that sinking noice every time you come to a halt.
Cant say I notice it , as mine pulls away superbly, if you wanted more grunt for waterskiing then it would probably make sense to keep hull from flooding.
Please remember this flooded hull at trolling speeds in very bad conditions will give the boat more stability