moveable ballast water pickup?

[unkiemotorhead]

Wizards, I've seen a water pickup (on a 28' Skater) that could be lowered into the water while underway to fill nose ballast tanks, and then raised to either seal or drain the ballast tanks...either way, no drag since it was raised above the bottom of the boat underway. Haven't yet found such an animal on the net. Before I go build one, might any of you know of something artful out there like this? I've researched all the ski boat stuff and found it's mostly pump-driven. I could do that, but the no-pump external transom setup on the Skater seemed to be the cleanest since no pickup in the water unless filling the tanks. I could use a pump to drain, but I still favor the "almost never in the water" pickup option. Suggestions? tnx! unkiemotorhead

[Mr. Demeanor]

How about a 3 way valve and one pickup. One position fills from pickup, one position closed off, one position drain to a through hull. I have a setup like this on my Fountain fish boat for the livewell and washdown. I can draw from the ocean, fresh water tank, or closed.
Mount it within easy reach while underway.
Look at Graco for valves.

[unkiemotorhead]

thanks! I'll ponder that. A key attribute needs to be: pickup out of the water when above, say, 30mph. But since this is a deep V hull, perhaps I could place it out wide from center where the V is still seeing water at low speeds, but no water at high speeds. Alternative to a pickup that I can swivel or slide vertically. Graco. Tnx! unkie

[Mr. Demeanor]

I have a transom mounted pickup but mines also a tunnel hull. Heres some info on mine. The little notch feeds water up into it.
http://www.screamandfly.com/showthre...t-water-pickup

[Revolution141]

Very common in water ski racing circles. Most are custom fabbed.
All you need is to have it made with bottom half of pickup sleeved inside top half and set up with a standard throttle cable to somewhere near helm. Just have it hooked up to a shift handle. Push handle to the floor one way to push the pick up down into the water then pull up to retract above water line. A 1 inch pickup fills a 200L ballast tank in about 30 sec at roughly 50mph. Then just have a bilge pump mounted in tank to pump out when needed. I have a 3800gph pump that will pump out the same amount of water in roughly the same amount of time. Very simple and effective!

[unkiemotorhead]

Very common in water ski racing circles. Most are custom fabbed.
All you need is to have it made with bottom half of pickup sleeved inside top half and set up with a standard throttle cable to somewhere near helm. Just have it hooked up to a shift handle. Push handle to the floor one way to push the pick up down into the water then pull up to retract above water line. A 1 inch pickup fills a 200L ballast tank in about 30 sec at roughly 50mph. Then just have a bilge pump mounted in tank to pump out when needed. I have a 3800gph pump that will pump out the same amount of water in roughly the same amount of time. Very simple and effective!

Perfect. Before I found your reply here, I'd designed the pickup, found the Teleflex and hardware to do just as you say. Thanks for this since it reinforces my thinking! I have a hobby machine shop so this'll be easy.

The fill rate you cite is most interesting. The Skater I rode in did just that. Your approach deletes the two-way pump option that wakeboarder ballast systems seem to use, and allows the use of just a simple bilge pump to dump the tank as you say. Slick.

I'm planning on a ~30 gallon ballast as more than enough, based on my experiments with good'ol sandbags, so this will fill and drain quickly.

I appreciate your input!

unkie

[Revolution141]

No problems.
i wish I had a good picture of mine to show you. I'm away for work until next Wednesday, if I remember I'll take a photo and show you. I think you get the jist though.

One word of advise is to mount and setup so when extended to pickup position only needs to protrude 1/4 - 1/2" below bottom and mount as close to engine bracket as practical. Obviously slash end of pickup with a 45deg angle (or alternatively fabricate so that tube bends forward and faces direction of travel/transom.)

Make sure you have an overflow on tank and plumb to a skin fitting on side of boat where you can see it and most importantly make sure hose and outlet is at least 1 1/2 times larger than pickup. Otherwise the tank will pressurise and split tank.

[Revolution141]

Just found some pics of mine!

[unkiemotorhead]

Yup. I'd concluded that the pickup will probably explode the ballast bladder, so I've found one with two vent fittings. Can get a tank to fit so I'll use a wakeboard soft tank, about 30 gallons. A little more than I think I need, so don't have to run it completely full...and often don't need the weight at all. The passengers and I can see the bladder tank as it fills, so we can double check as it fills to prevent destruction, but much larger vent lines than inlet lines makes total sense. tnx for confirming! I had not drawn conclusions regarding how far below the bottom of the boat to run the pickup when fully extended downward, so my design uses a split collar to limit downward travel while I experiment. 1/4" to 1/2" down that you recommend is easy to set up...tnx!

and tnx for the fotoz!

unkie

[Mr. Demeanor]

Just throwing this out there but if you mount the pickup like I did in the thread I linked its slightly above the bottom. You just need a very small groove to feed it. Water will try and wrap up the transom into the tube and fill when the valve is open. No moving parts at the pickup which seems like a lot less rigging headaches and no drag when its in use or not.

[unkiemotorhead]

yup, that's certainly very clever! And thanks for the detail! But I have to be true to my MechE/hobbymachinist/welder/mechanic tendencies and make something more complicated with moving parts and wires and pumps and levers an fittings an stuff... :-p And I raced little outboards for years so just can't add any drag down there unless I need it.....not logical, not measurable....just my thing. :-)
unkie

[Revolution141]

Just throwing this out there but if you mount the pickup like I did in the thread I linked its slightly above the bottom. You just need a very small groove to feed it. Water will try and wrap up the transom into the tube and fill when the valve is open. No moving parts at the pickup which seems like a lot less rigging headaches and no drag when its in use or not.

As long as the water is hitting that pickup all the time it would have to be creating drag. Doesnt matter how far above the bottom you mount it and groove the bottom. If outright speed isnt a concern then not a real problem but for what we do its everything! The setup youve shown is commonly used for an external water pickup to feed engine (not sure if thats the purpose of yours?), its a necessity in that case.

Other thing ive seen done, but needs to be built in during hull layup ideally, to dump the water is a 2-3" pvc pipe glassed to floor from the ballast tank back and out through the transom. It has a ball valve near driver to open to dump, youd be amazed how fast that water siphons from the tank at speed! No pumps or anything to fail.

[Mr. Demeanor]

My thinking is that with the valve closed that pickup would be full of water and once full and pressurized almost like it was just a little extension off the running surface if that makes sense. I think the drag would extremely minimal. I do understand your need to create however