To scupper or not

[demolition_x]

video...

http://www.youtube.com/watch?v=http://youtube.com/watch?v=Rzo6y-Z_u18


correct though. if the water does go above the end of the hoses on the outside the hood it will fill with water im not denying that.

it doesn't matter about the weight. but theoretically water will not come through those hoses unless the outside water level is above the ends. thats all i set out to prove. now the question is will the water site below or above the hoses when the ski is flipped... i have no idea.


if water is leaking from the hood seal or pole bracket then the boat is sinking regardless scupper or not.


im not going through school to be an engineer for nothing

 

[Matt_E]

Weight does matter. Try it with a steel cup.

It will sink.

 

[Boris]

The stock setup relies on trapped air in the bilge to add buoyancy to the hull keeping the breather tubes above the water line when the ski is inverted.
When you relieve that air pressure the hull quickly looses buoyancy and starts to sink dragging the breather tubes below the water level.


My "pool style" pole breather tube extends all the way to the bottom of the hull instead of just barely making it past the pole bracket.

Don't bother with a cup, I tried it with my ski when I firs put the scupper in.
I held the scupper shut with my hand and the ski was doing OK. The moment I let go the scupper there was a rush of air and the hull started going under.

 

[demolition_x]

im just proving that water is not gonna rush out of those tubes when the ski is upside down unless the level outside the ski is above them.

it very well be true that the front tube might be under when the ski is flipped. i have no idea. theres a bunch of other factors that cannot be factored in. this is only one small part of many.

 

[Matt_E]

Doesn't matter where the water level is. As long as there is an escape path for the air bubble, it will sink.
Edit: I suppose this problem could be simplified by cutting open the bottom of the hull. Would the weight of the hull & motor cause it to sink?
Yes, I believe it would.

I will admit that the water ingress from other areas contributes.

You would probably slow the sinking by fixing those areas. Which is what I intend to to over the winter, but at this point I don't think I'll put another scupper in.

 

[wetjet701]

hey guys what I did was install an automatic bilge on the underneath of my hood so when it flips it starts pumping and you got plenty of time to get back to it

 

[Matt_E]

That's an awesome idea. I don't like the idea of having wires going from the hood to the hull though.

 

[superramjet]

I've always believed scuppers sink boats. Roll your boat upside down in the water and watch your flap (if you can see it) it will open up from air leaving the inside of the hull. The flipside is the bilges leave a 1/2inch or so of water at the bottom of the hull that dont have drains and that gets kicked all over the engine compartment when doing tricks. Id love to have a way to close off the scupper tube when trying tricks that the boat might land upside down or when tying off to a boat or dock. I reluctantly went with a scupper in my latest build because I felt it was the lesser of the two evils

 

[suva]

Matt, why don't you add some floatation to the pole instead?

Or just hang on to your ski rather than flinging it away like a little girl scared of a booger?

(J/K)

lesser of the two evils

I agree

 

[oxnard111]

I am currently running on my FX, 2 3/4" duckbill valves on 3/4" sch 40 pvc pipe like joe b described. So far no major issues...but then I haven't done any "ghost riding" unmanned ,long duration, upside down surf rides. Basically, I use them for wash down. I'm tired of siphoning out (and getting mouthfuls) of bilge water. Pro-Freestyle guys might still need those big dump valves W/big pumps.

i haven't finished this thread yet, but I really like that idea. Looks really good, and no chance of breaking them off.

I am running one dump tube out the back of my ski with a duckbill, only b/c it came on the ski when I purchased it. I have no complaints yet. I'm running one pump in the front of the engine and one in the back, and I rarely see much water come out the electric bilges. Seems to get all the water out thats neccesary.

I have had my ski upside down once in the surf since having this hull. I was away from my ski for about 20-30 seconds; flipped it right over and started right up.

 

[Matt_E]

Matt, why don't you add some floatation to the pole instead?

It wouldn't help upright the ski, because the pole stays where I leave it set, and when it's upside down & away from me, that's usually right on the hood.

Or just hang on to your ski rather than flinging it away like a little girl scared of a booger?

Because fixing the ski is easier! :biggthumpup:

 

[D Slicker]

Demo, if you turn the cup upside down then you will be more like the situation we are taking about.

 

[demolition_x]

Demo, if you turn the cup upside down then you will be more like the situation we are taking about.

all i was proving was this:

Water will indeed come through those intakes when it's upside down.
Remember - that ski (particularly the bilge) is heavier than water. It wants to go down. The only thing holding it up is the air in the bilge.
And that air has a nice easy escape path through the scupper. -Matt E-

water will not travel up those hoses unless the level outside is over the end of the hose

 

[Matt_E]

See my simplified example.

Will it sink with a hole in the top (bottom of the hull).
Yes, I think it will.
Ski's heavy, and there is some water ingress from the pole bracket and hood seal.

 

[demolition_x]

again....... im only talking about the breather hoses in the hood NOTHING ELSE.

water will not come out of those hoses unless water is above the hose.

 

[oxnard111]

again....... im only talking about the breather hoses in the hood NOTHING ELSE.

water will not come out of those hoses unless water is above the hose.

i understand what your saying... kinda makes me want to lengthen my breather tubes, but then if you do that, will it affect your riding when the boat is right side up? Like if you going, alot water comes in the compartment, and the engine chokes out b/c the water level has already hit the tubes?

 

[Matt_E]

Lengthening the tubes won't help (much). You will have water ingress elsewhere, and the scupper will sink it.

 

[oxnard111]

Lengthening the tubes won't help (much). You will have water ingress elsewhere, and the scupper will sink it.

I was kinda referring to that scenario without a scupper. sorry I should have clarified.

 

[Glory_Freestyle]

I use an adjustable spring loaded check valve in my ski and it definitely seems to work better then a scupper as far as not letting air out. I set the tension so the valve takes about a pound of pressure to open. It doesn't drain as fast as a scupper, but it's fast enough.

Here's my original thread about it.

http://www.pwctoday.com/showthread.php?t=8699

The link to the valve has changed to this: http://www.ndspro.com/products/Info.aspx?cat=316&class=Flo Control&tab=Overview

 

[Brenden]

do the scupper no doubt
bilges you gotta wait and wait for them to pump it out...and they breakk!!
just drill 2 holes in the ski put some pipe in attach the scupper...seal it all up welll and you'll be fine and dry

i dont even run bilges and my ski has never sunk...unless i let it sit in open water for a long time
:grumble: