flying SIB

Antonio · 21 July 2019, 08:28

hello guys, long time no see...

well, have came to a situation funny at least, I have a flying SIB, yes...

have an 380 ocean bay (china boat) with a 15hp 4st suzuki, and four of us usually came on board.

the thing is that at wot I'm almost lose control of the SIB beacause it take of the water plane.

perfect balanced, third hole trimm, 1/4 of throttle and we already are on plane, and the thing his that we came literaly of water.

to control it have to reduce to 3/4, on flat water, or on choped water, like today.

any help in solution this...

Fenlander · 21 July 2019, 09:12

>>>at wot I'm almost lose control of the SIB beacause it take of the water plane.

Is that with just you or with four people?

Antonio · 21 July 2019, 09:25

hello,

fully loaded, he just take of..., have to be very carefully.

when I say fully loaded, his with gas tank, ice box, ancor (4 kg), fishing gear, bag of spare clothes (jumbo bag), seat bag with all of things that you can imagine, bow bag with a tool box, plus safeting gear, and 200 kg of people.

Locozodiac · 21 July 2019, 14:38

Antonio,

Turn the Sib upside down and take a picture of the hull along the inflatable keel. Another one of the transom and attached motor to have a look.

Was the Sib and keel inflated to the factory recommended working pressure of at least 3.0 PSI with a gauge ? Finger gauge is nada bueno, it's very imprecise.

Happy Boating

Antonio · 21 July 2019, 23:13

hello tks for the replies

well regarding the pictures, will take them next weekend.

regarding the pressure, I do not have a pressure meter, always use the tubes, rock solid, why, because last summer, with the thumb meter, broke a floor board and twisted the stringers, funny, yes, because was only in november when I dismantle the sib that I found the present, until present day still not find any replacement material so make some (do it your self, and find a way that functions) and we live.

tks

Antonio · 22 July 2019, 10:54

another thing with the flying is that occurs with no front wind and with flat or chopped sea, as we have here in Sétubal bay.

chopped 0,5 to 1 mt with a 10 s period.

with 0,5 or little less I can wot.

with 1 mt ou 2 mt, some times occurs in the late afternoon, half throttle and here we go.

my sib as a funny shape, he seats on the water with only the three tubes (left, right and the middle one), between the tubes there are a hole, at least appears...

the flying sensation is first im only with the central tube, them he seats the left or the right one depending the weight distribution its crazy.

Locozodiac · 28 July 2019, 15:58

Read the whole post again but without pics of the hull, transom/motor ones will be near impossible to elucidate about the flying issues going on...

Happy Boating

Antonio · 29 July 2019, 17:11

photo history
https://vimeo.com/350737147
https://vimeo.com/350737077

Fenlander · 29 July 2019, 19:00

>>>with 0,5 or little less I can wot.

>>>with 1 mt ou 2 mt, some times occurs in the late afternoon, half throttle and here we go.

If I'm understanding you correctly... that over 0.5m and more so up to 2m waves you can't maintain WOT that sounds about normal for a 3.8m SIB.

Antonio · 29 July 2019, 21:24

Quote:

Originally Posted by Fenlander

>>>with 0,5 or little less I can wot.

>>>with 1 mt ou 2 mt, some times occurs in the late afternoon, half throttle and here we go.

If I'm understanding you correctly... that over 0.5m and more so up to 2m waves you can't maintain WOT that sounds about normal for a 3.8m SIB.

Fenlander, what I wrote was "half a throttle", not WOT...
in the videos we are 3/4 throttle in 0,5 mt chop in the afternoon,,,
nevertheless this sunday was a down to earth, we did not fly...

to obtain that situation we have to have tail win and flat water...

will put a graphic of our afternoon journey where you can see some data...

Antonio · 29 July 2019, 22:17

......

beamishken · 30 July 2019, 09:04

Quote:

Originally Posted by Fenlander

>>>with 0,5 or little less I can wot.

>>>with 1 mt ou 2 mt, some times occurs in the late afternoon, half throttle and here we go.

If I'm understanding you correctly... that over 0.5m and more so up to 2m waves you can't maintain WOT that sounds about normal for a 3.8m SIB.

Sounds about right to me too! Drive anything up a ramp fast enough its going to fly. Probably feels worse in a relatively flat bottomed boat.
I'd say either slow down to suit the conditions or buy a bigger boat or even a deeper vee rib. A deeper vee won't stop all the flying but it will make the landings softer

Locozodiac · 30 July 2019, 19:11

Antonio, some issues....

Is the flying issue (bumpy ride) happening too on flat, calm no wind water cond and loaded same ? Deck load distribution seems correct on videos.

It's quite normal to achieve a bumpy ride at speed as seen on first video on wavy water cond, less on a slight choppy sea cond and none on flat calm water cond. Now imagine that Sib running at open ocean at 3/4 to full throttle.

That Ocean Bay Sib of yours is not a known Sib brand, usually a Sib manufactured by a Third Party with seller's Logo attached. Would you say that the rear inflatable keel extends to where the transom area ends or way less ?

Ckecking pics would dare say that the bulb formed at front keel is much wider and taller than seen on most other brands sibs, front hull Sib relies much more on the keel than on their side tubes producing that bumply, flying water ride. That's why was so important to count with an up side down pic of the Sib showing the keel inflated to its recommended working pressure to have a better look than on an underwater one.

Inflate keel to say 2 PSI and test again with same load if the bumpy ride has lessened, if so, it's a keel related issue, won't call it a flaw as the Sib navigates in water well, not at a comfy ride at faster speeds though. Report your findings..

Happy Boating

Antonio · 30 July 2019, 21:03

sorry Fenlander, misunderstood your comments,

tks Loco, for the insights.

tk all for the responses, as we say here, if we cant deal with it, just accepted...