SIB performance

[Leapy]

Bought a Seago 290R (air floor, inflatable keel) last year together with a Suzuki DF5 outboard. We've only managed to use it once so far (too much time on the RIB ) but based on that one trip I'm wondering if I'm over-expecting from it.

The book of words with the boat (subsequently confirmed by email from Seago) says all chambers should be inflated to 2.5psi, which we did. This seems fine for the tubes but from reading around seems low to very low for the air floor and inflable keel (some guy on here recently is talking about inflating his floor to 12psi).

This months MBM has a group test of 14 SIBs in the 2.5/2.6m range - none of them Seago - across a very wide price range (£350 to £1350)

The words of wisdom from the test is that the performance of a SIB most probably is a function of the hull design...flat floor: poor planing, doesn't turn well, but light and small when packed; slatted floor: slightly better planing, still poor in turns; air floor with inflatable keel/V bottom: planes easiest, good in turns but heavier/bulkier.

When it comes to performance absolutely flat out two up with our Seago 290 we saw 8mph best and not a chance of planing. The best performer of the MBM group did 15mph two up on the same 5hp we have. Some of the test boats managed 6mph on 2.5hp.

Any views/thoughts/comments from owners of similarly sized and powered SIBs?

[lightning]

I've got a 2.6m Zodiac SIB (wooden floor but with inflatable V keel) and the engine is a Mercury 6hp.
On a lake it will do about 14.5 mph according to the GPS, with two of us on board. It gets on the plane easily, taking under 5 seconds from opening the throttle.

[thornbackflound]

Never checked me speed i have a 2.70 seago and a 3.3 outboard,on a flat day when you get them?lol, im sure i get more then 8mph , not much over ?wooden floor ,heavy anti slip mat and 2 of us ,2.9 longer so heavier how heavy are the people on board? and 5hp can all have effect on how the sib performs

[C-NUMB]

Have a old BRIG 300, very similar in size and weight(but wood floor, inflatable keel) together with a Tohatsu 3,5HP 2stroke. With me alone it planes nicely, WOT guessing close to 10 knots. Taking one light kid along, still on plane, but with two adults no chance to plane.

Guess the weight of the engine, gear and crew is pretty critical on such boat/engine size. How is it performing with only one on board?

[cyberstoker]

Quicksilver 2.5 with inflatable floor and keel and 4hp gets up to about 5 knots.

[Locozodiac]

Seago's are pvc 0.9 mm fabric made, so can hold 3.0/3.5 psi once on water with no problem at all including keel, air mat floors must have at least 10 psi for the floor to rock the least. Used to inflate my old 320 air mat floor sib to 12/14 psi (1 Bar)to perform near perfect. Air mats are no ballons, have thousand of crissed/crossed threads inside, can hold high pressure. A well inflated sib will perform much nicer, plane faster and handle load better.

Happy Sibbing

[Leapy]

Originally Posted by Locozodiac

Seago's are pvc 0.9 mm fabric made, so can hold 3.0/3.5 psi once on water with no problem at all including keel, air mat floors must have at least 10 psi for the floor to rock the least. Used to inflate my old 320 air mat floor sib to 12/14 psi (1 Bar)to perform near perfect. Air mats are no ballons, have thousand of crissed/crossed threads inside, can hold high pressure. A well inflated sib will perform much nicer, plane faster and handle load better.

Happy Sibbing

That's interesting...it goes against the handbook and against the email from Seago but seems to be in line with what others have told me.

I'll give it a go next time...if you hear a loud bang you'll know what it was

[Leapy]

Originally Posted by C-NUMB

Guess the weight of the engine, gear and crew is pretty critical on such boat/engine size. How is it performing with only one on board?

Haven't tried one-up. Another of those next-time-things-to-do.

The engine weighs 19kg...the other half and I about 160kg together.

Hmmm. The boat weighs 30kg or so...engine 19kg...crew 160kg. I wonder where the problem is

[lightning]

Where are you testing your boat? I found that ours would not exceed about 5.5mph on the canal (not that you'd want to), it just produced a large following wave and the bow came up. This led me to believe there was something amiss with the trim etc.
However, we took it on some open water and it shot up to 14mph+ two up with no trouble at all.

[Leapy]

Originally Posted by lightning

Where are you testing your boat?

On the Fal Estuary...a touch wider and deeper than a canal

I think it down to weight, modest power and me expecting too much