Decisions, Decisions...

[Sib_shark]

For the last two years I have enjoyed owning a Prowave 4.2m SIB. Its been well used for messing about inshore and even to catch some decent sharks off the Cornish coast!

I am looking for another ultra convenient SIB. I am curious about larger flat, air decks 3.8m+. In particular, stability and whether they are comfortable/safe to stand in when drifting /at anchor?

Any help would be appreciated.

[Chris]

What about an F-RIB.... I saw these at the boat show and they look really good.

[paintman]

Whereabouts off the Cornish coast & what species?

[philpot]

The only comment I can make here is gained from my first and last flat air floor boat, an Excel 330 which is really well made and superb warranties.
I had issues with performance due to air pressures which may not have been too bad if I had used a smaller outboard instead of using the max engine of 15hp. The floor pressure is critical to get the boat working at optimum and found myself asking for help on here as I had no knowledge of this type on sib.
On a 3.8 or there abouts I would think the floor pressure would be just as critical if not more so. I can only suggest getting further help from guys on here with more experience of this type of floor and to ask for a test run to see for yourself how well it performs before buying one.

Phil

[John Kennett]

Flat air floors are pretty wobbly, and the bigger the boat the more pronounced it will be. They are fine for flat water if you're not too bothered about performance, but I'd say that a 3.8m boat may be pushing it.

I had a 3.4m air deck with a 15hp 2 stroke and it sort of coped OK with a typical Solent chop, but the floor did move around quite alarmingly!

[Chopperbill]

Have a Saturn 365 with air floor. Floor is extremely solid when using the max. Amount of air is 10psi or 70kpa. Don't notice it moving around and is very comfortable to sit on as I have marine carpet over it. Saturn uses a wood board in the middle under the floor that goes from tube to tube above the keel. That may be why it stays in place. However, I don't run in extreme chop conditions.
Oh, I run a new Suzuki 20 EFI.

[Wozizname]

Hi Sib Shark and from your OP I'd say you have a 420 Sport HP-V.
With our type of floor/hull the air pressure is very important as others have mentioned.
The tube pressures should be .25bar (4psi) and the floor/hull .80bar (11psi).
After launching and the boat has been in the water 10-15 minutes you'll find the air pressures will have dropped off considerably (20-30%) due to the temperature differences which will allow plenty of flex and movement.
Adjust the pressures back to where they should be and you should find an improvement