Airdeck Keel Board Redesign

[Steve509926]

So the day was planned, the weather forecast was reasonable, not perfect but at least I would be out on the water for a couple of hours and put the new keelboard through its paces.

Got to the steamer carpark in Glenridding and it was clear that the weather wasn't as forecast. It should have been 8 mph winds, occasionally gusting 12, but this was more like 15 occasionally gusting 20. I checked the weather forecast again, and sure enough it had changed but the wind was due to drop. I had a chat with the people in the Steamer office and they confirmed the latest weather forecast.

Even though I wouldn't be able to test the keelboard with regard to a build up of air under the hull as it was to choppy for that to happen, I would be able to test if it was ok or not, so I decided to go out for a couple of hours.

The new keelboard completely exceeded my expectations. The airdeck is flatter, it doesn't have that slight hump down the centre where the keel pushes up. The airdeck feels much stiffer. It has increased WOT speed - the max I had achieved one up in Redneck in ideal conditions with the old keel boards was 16.6k, in very choppy conditions with a side wind with the new keelboard I achieved 17.8k.
But the unexpected and extremely pleasing benefit is it has changed the handling characteristics of Redneck. Rather than Redneck plunging into waves and bouncing back off them, it now tends to cut through the waves, handling is cleaner and more precise, it's feels like a completely different SIB. It has changed for the better

https://www.youtube.com/watch?v=MfuLdu-_7Fc

Oh, and yet again the weather forecast was wrong. On the way back to the slip, the wind increased so much that I was sat on the deck as far forward as possible to keep the bow down, travelling at displacement speed with wave crashing over me. I must have looked mad with this stupid Cheshire cat grin on my face

[Limecc]

Fantastic well done!

[Fenlander]

What a fantastic result. I am wary of flat air floor models as you will know from my cautious comments often when folks ask about longer ones in particular. But this mod seems to have taken away the potential for misbehaviour.

A typical bit of "catch you out" unexpected inland lake/loch weather.

[Steve509926]

It is certainly a mod that I would recommend providing you have the room in your vehicle to transport it. Rednecks performance improved considerably.

[jeffstevens763@g]

Nice result Steve

[Steve509926]

Couldn't have hoped for a better outcome Jeff.
Thanks for the epoxy advice

[jeffstevens763@g]

Originally Posted by Steve509926

Couldn't have hoped for a better outcome Jeff.
Thanks for the epoxy advice

[TmMorris]

Hi Steve,

When you refabricated the board did you ste the overall width so that the board sat in the V between the tubes and hull?

It seems to me like the factory boards are deliberately short and that if they didn't bend due the sausage keel they'd just remain flat to the u derails of the air deck as opposed to the ends bending down into the hull fabric?

I think I'm going to make a new board for mine and hesitant whether to make it fit the V or leave it short.

[Steve509926]

Hi Tim, the front delta shape is exactly the same size as the front board as supplied by Excel.

The mid board is just short of where the hull and tubes join, approx 15 mm short each side.

[TmMorris]

Thanks Steve. So they don't fit snuggly into the V between the hull fabric and the tubes? Effectively the boards are a means to add rigidity to the air deck?

If this is the case then the simplest solution for me would be a large sheet of phenolic ply.

The fact that the ends of the standard boards like to poke through the hull skin must be due to them curving away from the air deck when under pressure from the keel?

If I position the forward board where it is held by the straps on the air deck what stands out is that it looks to be completely the wrong shape.


Moving it forward around 10cm gives a better fit bit the angle of the cut is still notably too acute.

[Steve509926]

Originally Posted by TmMorris

Thanks Steve. So they don't fit snuggly into the V between the hull fabric and the tubes? Effectively the boards are a means to add rigidity to the air deck?

Hi Tim, if the boards are too snug, I found it difficult to fit and remove the new board.

Originally Posted by TmMorris

Effectively the boards are a means to add rigidity to the air deck?

Yes, which improves the rigidity of the sausage keel

Originally Posted by TmMorris

The fact that the ends of the standard boards like to poke through the hull skin must be due to them curving away from the air deck when under pressure from the keel?

That's exactly what I found with my old boards which were made of a very thin sheet of "carbon fibre" plastic. I was of the opinion that they would eventually cut through the hull pvc.
The new board does push out the hull a little but because it is thicker and the ends are rounded off I don't think it will cause any problems.

Originally Posted by TmMorris

If I position the forward board where it is held by the straps on the air deck what stands out is that it looks to be completely the wrong shape.


Moving it forward around 10cm gives a better fit bit the angle of the cut is still notably too acute.

Your front board doesn't look the same shape as mine.
My board is delta shaped and fits as far forward as possible whilst still allowing access to the sausage keel valve.

[TmMorris]

Thanks Steve. Really useful information. I've formulated a plan for a redesign which I'll put in the other thread to keep yours clean. Tim.

[Steve509926]

Looking forward to seeing what you come up with.