High speed turn with 9m. rib

Fjordrafting · 04 June 2004, 21:38

What is the normal way for a 9 m. rib with two outboards to handle if thrown into a tight turn doing 50 knots on flat water? Is it to slide sideways and suddely grab the water hard and then bouce to the other side throwing everybody in the water?

tim griffin · 05 June 2004, 06:19

silly question but are you trimming the engine in before the turn or leaving it up, if up you are going to lose grip and slide and bounce as you suggest
regards tim
www.griffmarineservices.co.uk

Fjordrafting · 05 June 2004, 17:51

I always go with the engines leveled on the middle, read from the meter, exept when accelerating.

tim griffin · 05 June 2004, 19:10

try trimming in more ie fully down for tight turns or maybe you need trim tabs as well to get her tracking better without seeing pictures or having a go its a bit of guess work really
any near you with similar setup or can you get access to manufacturer for advice
sorry not much help
regards tim
www.griffmarineservices.co.uk

jwalker · 06 June 2004, 00:54

I'm not sure I'd want to throw it into a turn at 50mph with full down trim. Depends on the boat but I'd take care.

John Kennett · 06 June 2004, 21:24

Agreed. You could quite easily end up with the stern overtaking the bow rather rapidly!

John

Cookee · 07 June 2004, 09:22

The only reason to do this is in an emergancy or for the RCD which is built up to slowly and should only be tried by a very experienced skipper!

If you're going to do it I agree with JW and JK - a bit of trim will give the bow less chance to hook and throw everyone out!
More trim also helps the boat bank a bit although this is dependant on the hull design.

Bajan · 07 June 2004, 10:32

Quote:

Originally Posted by Cookee

The only reason to do this is in an emergancy or for the RCD which is built up to slowly and should only be tried by a very experienced skipper!

If you're going to do it I agree with JW and JK - a bit of trim will give the bow less chance to hook and throw everyone out!
More trim also helps the boat bank a bit although this is dependant on the hull design.

What is an RCD?

Cookee · 07 June 2004, 10:38

Quote:

Originally Posted by Bajan

What is an RCD?

It stands for Recreational Craft Directive and is what you have to go through to get your CE mark so you can sell any boat in the EU.

Hope that explains it all,

jwalker · 07 June 2004, 10:39

Quote:

Originally Posted by Bajan

What is an RCD?

Recreational Craft Directive.

jwalker · 07 June 2004, 10:40

What fast fingers you've got!

Bajan · 07 June 2004, 10:42

Thanks for that guys!

gtflash · 07 June 2004, 21:33

i was under the impression that in order to turn tight you should always (boat dependant)trim in before you turn to settle the nose back in the green, obviuosly if you did it mid cone then the sudden change in hull ton he water could cause a hook.. but if the nose is already driven back down into the water is it not ok?????

John Kennett · 07 June 2004, 21:40

A bit of nose down trim is fine, and you certainly wouldn't want to have the engine trimmed out.

The potential problem is with trimming the bow hard down as this could result in the boat "hooking" as the bow digs in and the stern lifts.

John

gtflash · 07 June 2004, 21:45

what even goin in a straight line? i didnt really think that was a problem until extreme high speeds!! 60 knots + im gonna have to have words with my rya instructor as he told me different on my 2

Alan · 07 June 2004, 22:01

Isn't the point here that it somewhat irresponsible to bung a 8.5m RIB into such a sharp time that it chine hops with a boatload of pax onboard?

gtflash · 08 June 2004, 05:49

i suppose it depends on ur driving requirements, if ur cruising with a bota full of ur family yes maybe but if ur racing no its probably essential to a point, however im confused cause some of you guys are telling me different things to what i have been told on my rya courses....

John Kennett · 08 June 2004, 08:47

Quote:

Originally Posted by gtflash

what even goin in a straight line?

No, "throwing it" into a turn at 50 knots!

John

seahound · 08 June 2004, 20:34

When doing the turn, use your trim tabs (if you have them, if you don't then fit them) instead of the engines. If you are doing a sharp right hand turn then drop the right trim tab, you will find the boat tilt over to the left, but when you turn to the right the boat will remain level and the props will keep the grip and stop you sliding.

Handy if there are remote trim tab switches on the co pilot side, and a co pilot !!!!

Mikey · 08 June 2004, 20:51

If it helps, we have also found it behaves differently based on the props!

On our boat with 4 blade props (cleavers or Bravos) trimming right in on a tight turn tends to push the nose down more and cause the boat to bow steer and ultimately hook. Better at level trim or slightly in from level into the turn.

With three blades, you can trim further in, but somewhere between level trim and fully in is better than fully in.