unsinkable ski

[SharkB8]

On our last surf ride of '09, three of the four skis me & my friends rode were sunk and had to be towed in. It was a wild day (9 feet, 9 sec interval) but still I don't know why someone hasn't invented an unsinkable ski yet.

Can someone tell me why the following idea would not work? If it were possible, I think someone would have done it by now.

The air intake pipe goes all the way down to a "box" on the bottom of the hull. This box has a valve that electronically opens and closes. The box also has a way to tell when the engine is running. If the engine stops (ie, you fell off and the lanyard killed the motor), the valve closes. If the engine is running the valve opens.

Maybe you would need two such air pipes to get enough air for a modified engine, but it doesn't sound impossible to me. Some bright up-and-coming engineer should go invent this.

 

[OCD Solutions]

Use the powervalve motor off a yamaha gp to actuate it. It opens as soon as you crank the ski over and then closes a second after the ski stops. Only problem is that it is somewhat variable, it would need to be modded to function as full open or closed.

Anyone who snorkels wil see a downfall, once full, the tube needs a way to be purged or drained, otherwise the water in the tube will be the first thing thru once the valve opens. Alot could be accomplished with simple pipe routing to seperate the water from the air.

 

[steve-uk]

bottom of the hull wouldnt work as you take on water no matter what you do .. cos if air can get in so can water, so if your doing subs, stabs etc the hull will fill with water which if the airbox is at teh bottom you would then injest water into the motor

also what happens when you end up with the ski upside down in the water and the motors still running... done that many times.. sometime we dont always wear the lanyard

 

[WFO Speedracer]

I have mentioned something like this before,why not run it off of engine vacumm,when the engine is running vacumm pulls the air intake doors open,when it dies they close,no excess current draw,no switches or solenoids to break.The pulse can be turned into vacumm by using a one way valve in the line.

 

[restosud]

ok geniuses.how about the exhaust then?

 

[WFO Speedracer]

ok geniuses.how about the exhaust then?

Anything you put into the exhaust will cause a restriction,use an exhaust scupper like River rat is coming out with to seal off the exhaust .

 

[SharkB8]

Anyone who snorkels wil see a downfall, once full, the tube needs a way to be purged or drained, otherwise the water in the tube will be the first thing thru once the valve opens.

That would only be a gallon or two, right? Nothing a bilge pump couldn't handle once you're upright and running again.

 

[WFO Speedracer]

My idea was to actually install the flaps in the hood air intakes,the drawback being you would have to disconnect and reconnect the hose when you remove the hood each time,a quick disconnect should make this fairly simple.

 

[SharkB8]

bottom of the hull wouldnt work as you take on water no matter what you do .. cos if air can get in so can water, so if your doing subs, stabs etc the hull will fill with water which if the airbox is at teh bottom you would then injest water into the motor

I'm not sure what you mean by airbox. I don't think I explained my idea very well.

I haven't measured it but when my squarenose is sitting upright, it looks like the two air intake hoses extend from the hood down to about 6 inches from the hull. When my ski is floating upside down, water doesn't flood in through those hoses because they reach "up" (now that the ski is upside down) above the water level. So I don't think that extending those hoses a little further so they they almost touch the hull would make the situation any worse.

So if you're with me so far... I was thinking that these magic electronic valve boxes could be secured to the hull. That was the idea.

However, now that I've thought about this a little more, maybe there is no need to extend the hoses at all. If the valve mechanism were light enough, maybe it could simply be secured to the end of the hose.

I wasn't really thinking about this idea for subs etc. I do know that when it takes me a minute or two to swim back to my ski while it is tumbling in the surf, I would feel a lot better knowing that the two air intakes are sealed off.

 

[Laserman]

I think it would also help to foam fill ALL the "dead space".

I crashed my first JS550 shortly after buying it. I decided to fill the front with foam around the water box and such. I ended up filling the whole front with foam.

I had some water issues with the ski after that, and it would never sink even as far as the hood.

My next JS550 had no such mod, and the first time it took on water, all I had showing were the ends of the back rails and the top of the handle pole.

I wanted to add this info in ADDITION to what you all are talking about, becasue the OP said the skis "sunk", not ingested water.

I think foam in all the unused open areas would be part of making an "un-sinkable" ski.

Are all the handlepoles filled with foam? I would think that would help also.

 

[dajnglst]

I can share diagrams with a few for a sealed mechanical design for intake, waterbox and exhaust outlet....

All of which can be applied to the air intake in hood or handpoles. The tricky bit about mechancal design is the lever ratio to operate from handle bar and trigger everything. A hydrualic system with resevoir and solenoid would be prefferable. Just have to design res tank and small pump to prime system up again so that handlebar operated mount is simple as kill switch. Trigger solenoid and dump hydrualic pressue to slam everything closed....

Hood seal designs are a joke also... The surf ski has the best design I have found with inflatable inner tube to seal of hood to hull. Ten speed bicycle tubes would fit hood lip are well, just have to find someone willing to mold them. Figured beta bits could be made from vinyl water tank material RF welded....

Water proofing the thing for a small surf swamp out is no biggie, it's the spring load you need for the exhaust outlet when the thing is swallowed in 15ft surf.... So hydrualics are the answer....