new member new SIB couple of Qs

[exeboy]

Hi guys i'm a new member but not a new user,
I was floating about the forum (unregistered) a while ago doing a bit of reseach before making a purchase (quicksilver 340 airdeck + 15hp tohatsu) secondhand

I'm not new to boating but have never had a performance/airdeck inflatable before,
its great, I love it, but so far my experience has been a little disspointing...

when on the water i accelerate up onto the plane but shortly afterwards the floor begins to balloon up under me then the water balloon travels back out from under the floor/transom and then over the transom into the boat!!
So thus far my high speed thrills have been limited to about 20 secs on my first two outings leaving me to tootle about not quite on the plane (very frustrating) is it a inflated pressure problem? Or outboard trim problem? Or am I being Thick?

corect me if i'm wrong please

tubes 3.5 psi
airdeck 10psi
keel 3.5 psi ?

i didnt get any paperwork with the boat, this is information ive sourced from the net.

Outboard is a 2002 thohatsu 15hp s/s in A1 condition it does have what i know as dolefins fitted but mine are marked as hydro sumthing (i cant remember) On a 15 why? could these be my problem? the trim setting/bar is set at the lowest setting.

any help and advice is very much appreciated and needed as i dont get many chances to get out (reason for the downsize) and so far its been frustrating i know the boats good so it must be me being thick confused in some way.

Tim

[oujakov]

Hi and welcome to the forums.

We have similar setup. I've QS 330 airdeck with 15hp Johnson.

It is a great kit for 2 adults + 1 kid, and it can perform rather well. The key for performance is to keep the thing an bodies balanced inside the boat.

I've played with tilt/trim settings with my engine and noticed that the best is to keep motor set at the position 1, closest to the transom and keep driver/passenger sitting towards the middle of the boat, just in front of the 1st bench. Kids or luggage to be kept around the bow. This way you get on the plane fast and spend way less time in the out of the hole position, e.g. bow raised way up before planing.

[matt h]

airdeck 10psi
keel 3.5 psi ?

pressure looks very low to me, i had a Avon 340 witha 9.9 f/s as Nos will vouch, same problem, floor was not rigid enough, and would buckle once it was on cold water,and outboard cavitate badly i had to sit centrally towards the stern, i found it was not possible with a foot punp to get that high pressure, im sure its a shit load higher pressure the 10 psi, the floor has to sound like a drum when flicked

The quicksilver has a very shallow V hull, Not the same as the bombard.

the Bombard floor had to be nearlly solid and worked a treat, i pumped it up using a bravo 12 electric pump to achieve the right pressure and it flew.

[jyasaki]

Pressure may be right, but you should pre-inflate before launching, allow to cool in the water for a bit, then recheck pressure.

The water will draw heat from the air in the tubes, lowering the pressure. Especially true if inflating out of the water on a hot day in direct sunlight.


jky

[exeboy]

Thanks for the replies guys, i too am using a bravo 12 pump but am maybe thinking after reading previous topics about the pump that the gauge is not that accurate.

So if this was the case i could turn it up beyond 10psi for the floor (when its pumped up the floor isnt like a drum can stil push it in with my finger etc)

worse case scenario when would the tubes etc blow? not at 4psi for example or even 12 for the floor? or would they

weight distrubution wise, setup is fuel up front (25l) and me as far forward as possible kneeling just behind the seat up front

colder air being denser i havnt thought of until now, bit of a pain inflating dropping in the water for a few minutes carrying out and reinflating must be able to over inflate to a certain degree to compensate surely? any boffins now by how much?

[m chappelow]

have you tried it without the doel/hydro fins ,,they can cause a few problems with short boats ,,anyhow its not a bad idea to remove them every now and again to see if corrosions staring on the cav plate and bolt holes ,,,,with my boat doel fins only slowed it down and dident seem to make any difference to getting on the plane any quicker or holding it there ,so i removed them ,

[Leapy]

Originally Posted by matt h

im sure its a shit load higher pressure the 10 psi, the floor has to sound like a drum when flicked

10psi? Are you sure? My Seago 290 manual says the tubes should be 2.0-2.2 psi but it says nothing about the floor and keel so I inflate them to the same figure.

I'd welcome comment from others with SIB's whose owners manual gives specific recommendations for the floor and keel pressures

[exeboy]

I have also thought that too, I always thought that they were best suited for towing etc seem a bit pointless on my boat, after all theres not a great deal of weight to it.

Leapy take alook at this which i am basing it on

http://sites.mercurymarine.com/pls/p...01_ENGLISH.PDF

[RibinSpain]

I have a Zodiac 3.4 Yam 15hp.

I now put the fuel at the back by the transom & we lay across the floor, legs over the opp tube. Helm uses seat as arm support.

That way we keep the weight central, we can all hang on & if 3 of us, 2 face 1 way, 1 in middle faces the other.

Seems to be far more space. Keep the tube pressure hi & you can bomb along. If you get airborn less chance of flipping it over.

Sitting on the tubes is awfull unless you are about to go in the water.

Hope it helps

[matt h]

10psi? Are you sure? My Seago 290 manual says the tubes should be 2.0-2.2 psi

the tubes are set at 2/3 psi but its the floor that should (if its a airdeck) be very stiff, you should not be able to dent it with your finger, i just cant remember what pressure,im sure it was loads more than 10psi, check out manufacturers web site
have a brochure which actually does not give the pressure but it descibes it being tough and rigid and also resistant to bending!!

just check out your link, its says 10 psi so i wouldnt exceed that, if your still getting the problem like i did with the Avon 340, sit in the middle which pushes the keel out further or sell it and buy a aerotec!!
I could not put up with it as i was driving a waterbed, it was all too flat underneath and no real keel apart from the silly little one up front which was as usefull as a ashtray on a motorbike

Hang on, Jk should know, whats the floor pressure on yours??

[John Kennett]

From the manual:

Tubes 3.6psi
Floor 11-12psi
Keel 6.4psi

Sounds like your floor and keel are way under inflated. Get a decent stirrup pump with a pressure gauge. The Quicksilver one is good (I've just bought another one because mine is going with the Quicksilver that I've just sold!).

[Leapy]

Hmm. From my Seago manual now I look more closely...tubes 2.25psi...air floor 3psi...no mention of the keel

[exeboy]

thanks for that john, just to check thats the manual for the quicksilver not the bombard yes?
Next time out i will use your figures and let you all know how it goes.

[John Kennett]

Yes, that's direct from the Quicksilver 340 Airdeck manual. The pressures for the Bombard are much the same though. The main rule of thumb seems to be that these air floors need to be pumped up much more than you would think!

[Locozodiac]

No matter how well you inflate the floor to it's correct working pressure, will still rock a bit, it's the nature of the little beast, portability versus perfect performer as compared to wooden or aluminum floors on same size sibs.

If your Tohatsu engine is not splashing water against transom do to improper transom height for this engine use, place engine thrust rod trim angle in a position so that the anticav plate is at 90º with respect of bottom hull and boat is paralell to water when on full plane. Place weight towards middle/bow.

Get yourself a good brand pressure gauge, and inflate sib as stated by the manual.

Happy Sibbing