Trim

[Mark Halliday]

Originally Posted by Pete7

Could be a very lucrative contract asuming the the tall one only takes a small cut for using his forum for biz

I bought him a pint of Guiness at LBS in January. Do you think that would be enough?

[Scary Des]

Originally Posted by Pete7

Hmm, just thought, water pressure going to be quite high and would push against cables. Not sure if it would work with cables in compression as tabs might move up......

Could all be done with pivots and levers the nice thing is that you only need 35mm movement at the wedge (for Volvos’ system) and it wouldn’t be unreasonable to have 350 mm of movement with a lever so straight away you got a 10 to 1 advantage. Additionally you could get the cables to pull the wedges into work which would make them more capable.

Originally Posted by Pete7

....Fancy going halves:.....

Healthy price

Originally Posted by Pete7

Slues gate ? is that like a vice ?

Spelling let me down again what are those lock gate holes with a uppy downy doors Des

[Pete7]

You mean sluces. Your only going to get half a turn so the thread would have to move 35mm in half a turn, thats quite a steep thread, like a wooden cork screw removing thingy.

Where are all those honourably graduated students when you need one to work out the dynamic water pressure at 25 knots

Healthy price

ah but you only need two so we could go halves.

[Scary Des]

Originally Posted by Pete7

....Your only going to get half a turn so the thread would have to move 35mm in half a turn, thats quite a steep thread, like a wooden cork screw removing thingy.,.........

Maybe that is the answer instead of a lever you use a turn wheel 5mm wedge movement per turn. 7 turns for full wedge would be a coarse thread though Beginning to see why Volvo use electrics. Des

[jwalker]

Originally Posted by Cookee

If it says that they are effective up to 50mph, has anyone any idea what they would be like on a 60 - 70 mph stepped hull RIB? Thought about fitting trim tabs to the race boat, but they are heavy and bulky - these seem neater and more compact - maybe lighter as well?

How about 2 of them on each side of the hull. If you could calm the turbulence behind them, that'll save you making steps.




-------------

Originally Posted by pete7

but still think the water pressure might over come the friction of the cable and lever. However that would mean they automtically raise at a given pressure, say planning speed.

Because the transom is angled, you might find there is a tendency for them to pull out once they catch the water.

[Mark Halliday]

Come on guys. You are not going to need that much pressure to actuate the blade. It is going up and down across the flow. The major resistive force is going to be the one trying to jam the blade in its guides and drag the whole shooting match off the transom.

err...........I think.

[Pete7]

Originally Posted by jwalker

How about 2 of them on each side of the hull. If you could calm the turbulence behind them, that'll save you making steps.

Sounds like a hydrafoil, that would make Cookee popular on the race circuit

[Mark Halliday]

You could use a simple cam arangement.


Plan A concept............

[Scary Des]

The blurb from Volvo has just arrived in the post and it is no more informative than the stuff on the net
Having said that, it does have a price list a 300mm interceptor is £58 and a cable is £15 so for £75 and a 3 way switch from the shed I could get level the whole kit is £275

Des

[hard1]

But i think you may need the 450mm Interceptor based on weight/length?

[Scary Des]

Originally Posted by hard1

But i think you may need the 450mm Interceptor based on weight/length?

Possibly it is boarder line.

What I can’t decide is if I need two or not the only thing that worries me is my boat leaning and it always leans the same side Des

[codprawn]

Originally Posted by Mark Halliday

Come on guys. You are not going to need that much pressure to actuate the blade. It is going up and down across the flow. The major resistive force is going to be the one trying to jam the blade in its guides and drag the whole shooting match off the transom.

err...........I think.

Quite right - very little force needed to actuate the thing!!!

You can fit 2 each side - they have the cabling to do it - no doubt you could fit more.

Amazes me the people who get so annoyed at splashing hulls don't seem to mind splashing other things.....

As I always have said - there is very little truly new out there - INCLUDING hull designs!!!

I also wonder why Volvo only say "up to 50mph" - I can't see that they won't work at 51mph!!! Maybe they lose effectiveness at higher speeds - or possibly even they become TOO effective!!!

[hard1]

Originally Posted by Scary Des

Possibly it is boarder line.

What I can’t decide is if I need two or not the only thing that worries me is my boat leaning and it always leans the same side Des

Er, if you don't have two or multiples thereof, you will be leaning/listing somewhat when you deploy it. You must mount 2.

Some hulls always lean into the wind when planing, and these wedges look to be a good way to correct this. Does the PAC22 naturally list at rest or is it an outdrive alignment issue?

[Hugh Jardon]

Originally Posted by codprawn

I also wonder why Volvo only say "up to 50mph" - I can't see that they won't work at 51mph!!! Maybe they lose effectiveness at higher speeds - or possibly even they become TOO effective!!!

perhaps at speeds above the 50 mph range the forces on them become too great and they can crack or break

probably the cost/strength/size/weight consideration

[Scary Des]

Originally Posted by hard1

Er, if you don't have two or multiples thereof, you will be leaning/listing somewhat when you deploy it. You must mount 2.

Why If I fit one on the low side it will bring it level ie loose its list, or am I missing something

Originally Posted by hard1

..... Does the PAC22 naturally list at rest or is it an outdrive alignment issue?

Level at rest it is a torque issue Des

[DGR]

Maybe above 50 mph the drag they create to do their job has got to the point were there is little (or maybe even -ve) overall benefit?

It would be interesting to see what happens to their 7m model at those sorts of speeds.

D...

P.S. Mine has the same torque issue. 50 mph however, is never likely to be one.........

[hard1]

Torque yay! Turbo 4! yay! Now I understand. Yes of course a single unit would work, but it seems a bit odd just to fit one. This kind of thing, of course, is why tabs were developed. to balance out torque, wind, load etc. and promote early planing. From studying the hull of my Fairey Huntress, they fitted a boarding step at the stern across the rudder which was supported at the base by an extension of the hull for a width of about 2' and a length of around 14". This extra length, it was claimed, added about 2 knots to the top speed by extending the planing surface which is why I believe tabs are probably better in the long run although much more expensive. The racing boys could tell us much more I'm quite sure! Wedges or Tabs???

WE NEED TO KNOW......

[DGR]

The problem with only sticking one on one side is that you will add another asymetric feature to your hull - which will probably behave differently at different speeds......... ...which could possibly be worse......

[Mark Halliday]

Originally Posted by codprawn

Amazes me the people who get so annoyed at splashing hulls don't seem to mind splashing other things.....

Nah, its just inovative thought.

[Pete7]

Originally Posted by hard1

Some hulls always lean into the wind when planing, and these wedges look to be a good way to correct this. Does the PAC22 naturally list at rest or is it an outdrive alignment issue?

Mine leans into a strong cross wind as most boats seem to, but not at rest or when its calm. Des, wonder if its that gearbox ratio and large SMC 807 prop? You could do with having it measured.

Pete