Jack Plate Question

[Manos]

I spoke about this with FALCON they said is best to test the boat without it first. Just set the engine one notch higher than the recreational version and trim the motor from the engine's trim swich (which is mounted on the steering wheel - you should see this steering wheel is like bloody Formula 1 racing car with all these buttons on it)
However, with a 200 bhp VMax from what I can see on other racing RIBs a Jack Plate looks like is required.
I have the BIBOA rules and there is no mention about whethere I can fit a jack plate or not (will have to ask them I guess)
But for the sake of argument do you think I sould fit one or it will wasting money (they are expenssive about $ 1,500).

[Julian]

Hi Manos

I have seen a few race boats with these on mainly hard boats etc. They will help increase your speed but i'm not sure that they do the engine itself much good. Lift it too far and you may interupt the water intake etc. I have no idea if this helps to be honest,

Julian

[Dirk Diggler]

Without a doubt you will need an engine jack, but not the one in the photograph. You need a Gorilla from www.stainlessmarine.com , this is the one used by most racers. As for the problem of raising the motor too high, fit a water pressure gauge.

[Manos]

Thanks guys.

I have already fitted a water pressure gauge.
Right now I'm in two minds whether to fit a 150 bhp VMax and 650kgs weight or 200 VMax and 950 kgs weight.
As far as I know both engines have the same motor, gear ratio etc and the only difference is the carbs (200 VMax has bigger jets).
The boat tested already with both engines and various prop configurations and makes very marginally higher speeds with the 200 VMax. Honestly don't know if it worth’s the more money and the extra weight.
Thanks for the help

[Dirk Diggler]

Manos, these weights that you are quoting, are they max weight for entire rig in F2 for given HP, or do you think that a 200 Yam is 300kgs heavier than a 150 Yam.

Also, It sounds like this rib is not even built yet, ie, tanks on deck or under floor, but you have already fitted a water pressure gauge, but you haven't decided on which size engine.

Have you been eating lots of cheese before you go to bed?

[Manos]

For your info RIB is finished!!
Tanks were one issue that now is shorted.
Most gauges have been fitted. Jack Plate not necessary but considering.
Engine size is now a consideration but it looks 150VMax will be fitted. Found one for £3,000.00 NEW!!
Will post a photo of the RIB by the end of this week in the water with engine but not jack plate.
Boat shipping date to the UK 20th Feb with shipping company MCL. Do you want B/L number too?? LOL Just joking

The weights I quote are total boat weights with various engine configurations that are required for F2 i.e.

1 x 150 Merc (various types see rules) or conventional 2-stroke Yam 150 VMax boat min hull length 6.5 mtrs boat min total weight 650 kgs
1 x 200 Merc (various types see rules) boat min hull length 6.5 mtrs boat min total weight 900 kgs
1x200 Yamaha HPDI boat min hull length 6.5 mtrs min total weight 950 kgs.
To the above for extra 1 mtr hull lenght or part add extra 65 kgs

The above is a part quote from the new revised BIBOA rules.

[Scotty]

Is Jack Plate any relation of Jack Schitt ?

[gavin]

Manos have seen a Ballistic 7m I think with a 250 rude on the back they fitted a jack plate and ran it way up, bear in mind one other thing, when you hit big waves at speed the props leave the grip of the water, the tendancy for the motors is to rev right up or indeed over rev, you have the cooling water problem sorted, do you have a rev counter to watch the revs if the prop has insuiffecent grip or a rev limiter, just in case damage occurs due to over revving of the motor with reduced grip as the props are so near the surface, Jack plates look the part it is a cool idea gavin

[Manos]

Originally posted by Scotty
Is Jack Plate any relation of Jack Schitt ?

You are the expert Scotty you tell us
LOLOL

[Manos]

Originally posted by gavin
when you hit big waves at speed the props leave the grip of the water, the tendancy for the motors is to rev right up or indeed over rev

Thanks Gavin, I'm aware of that aspect. The boat has all rev counters, tem gauges, presure etc fitted o/b.
After having long discussions about the Jack Plate I think the general consesus is to skip it.
They look cool but do they halp in an off shore race. I think (from what I've heard) and what you also say that jack plates are good for lake/flat water racing (something I'm not doing any way - what's the point ) and not that useful for off-shore.
Thanks for the tips any way. Really appreciated