supra launch 21dd ballast

I am looking for some input on my plans to add some ballast to my direct drive launch. The boat is a 2000 launch 21, and it came with a hard tank under the rear seat. I am looking to add a bag to the rear storage locker, and one to the center ski locker under the playpen. My idea for the rear was to use a piggy back setup off of the overflow for the hard tank. My only concern with this setup is the current ballast vent location. The storage locker is pretty high in the rear, so the vent would be an inch or 2 lower then the top of the rear locker bag. I could try to add a loop in the vent line to get it a bit higher to allow the rear bag to fill fully. Would it be best to T off the current hard tank vent, or block it off and vent through the bag? If anyone has any experience with a similar setup, please feel free to chime in with some guidance.

The center locker is huge and easy. I am planning to add a reversible pump with dedicated feed and a dedicated vent for this front bag. I am looking at the 1200lb gravity games center bag wakemakers sell. It wont be able to fully fill, but I should be able to easily get 800-1000 lbs in it. Is there any concern with running a bag that will never fully fill? This bag is a monster and measures in at 88x19x19. If the bag is adequately vented it should conform to the space and bleed off the extra water through the vent, correct?

Last, I havent been able to play with weight in the boat at all. Does this hull respond better to weight in a certain area? I am reading front weight is better, but once again.....looking for real world input.

Any input is welcome and appreciated.

Thanks!

4n,

ive never liked a typical piggyback setup, especially using aerator pumps. 1) the flow rate slows dramatically once the hard tank is full and you start pushing water through it to the sac, which is often at a higher level. 2) you have to be careful that the hard tank is allowed to still vent freely. If not, it will tin-can on itself and can crack. This would occur after the sac has gravity drained to the tank and close off the vent thats now through the soft sac.

Having the filled sac higher than the cent or drain outlet, is certainly a recipe for passive draining. if you are going to list the boat for surfing, you can cross the vent and drain line to the other side. Do both sides.

Without knowing more about this particular ballast setup, I would consider giving each new sac, its own dedicated plumbing, leaving the original intact.

I purchased 2 reversibles for the new sacs. I could definitely keep the existing setup for the hard tank. I was just trying to keep it as simple as possible. 1 reversible for each zone. Since its a direct drive, one front zone and one rear zone. No plans to list the boat for surfing.


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I would possibly consider using an aerator pump for the rear-locker sac as that would allow you to get it full and while it would passively drain you would just keep the pump running all day long as long as you are wakeboarding without any issues.
Not sure the reversible impeller pumps are made for continuous operation or if that could eventually harm them?
They do also draw considerable more current.

You could possibly use Impellor pump -> hard tank -> T, First output of T -> vent, Second output of T -> rear sac.
Aerator pump -> rear sac -> vent.

That way if the hard tank fills first it could keep filling the rear sac, once both sacs are full you could use the aerator to fill the rear sac continuously, both sac and tank are well vented and you could use the impellor pump to drain both.
But as long as you can run the impellor pump continously this seems kind of "overkill".

At least with normal aerator pumps you would (regardless of what some people might say) never break the sac non the less crack the hull from the pressure of the pump even if the sac is totally un-vented. There just arent enough power.
As long as the pump is well vented shouldn't be an issue with impellor pumps either.

I would though consider the balance of the boat. You have a DD so pretty much weight up front already compared to my Launch SSV from 2001.
I have the 1100 lb (or whatever it is) GG sac that almost completely filles the entire ski locker up front, sounds like it might be that sac you are talking about.
With that full and no ballast in back the wake is crap.
I need at least the engine (what 600 lb?) and 800 lb ballast in back to get a decent wake. I run 2x 750 lb in back now and that is good when those and the front is full, they fill to about 600 I would guess since the space is not quite big enough.
If they are only 1/2 full or less and the front is totally full it is actually better to back of the front to maybe 2/3 full or so. With them empty I would go empty up front as well.

If you aim for 1100 lb up front with a DD engine I would aim for at least 1500 lb in back. Of course including passengers in the rear seat.

Just saying it might be just as good with a 800 lb up front or something like that if you tend to use the boat with only 3 persons (driver, spotter, wakeboarder). Now, I don't know what kind of bags you can fit in back?
I don't know if your hull might handle the weight differently either. But at least it is something to go by.
Though, by all means if you have 3 persons in the back seat (500 lbs) and the hard tank and rear ballast are about 1000 lbs together go for the 1100 lb up front.
When you are only 3 persons and want to have the biggest wake possible drop a 400-600 lb sac on top of the rear seat and you will be all good.

Good luck!

Mike

I am guessing I will have 700-800 in rear ballast weight with the plumbed in sacs. Yes, we are talking about the same GG sac up front. I dont think it will fully fill in my boat. So probably 800-900 up front. I figured i could partially fill the front to tune my wake?


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Quote:

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Originally Posted by 4nryde

I purchased 2 reversibles for the new sacs. I could definitely keep the existing setup for the hard tank. I was just trying to keep it as simple as possible. 1 reversible for each zone. Since its a direct drive, one front zone and one rear zone. No plans to list the boat for surfing.


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Oh, that changes things for sure.

Current plan is to try and get 800 of hidden ballast in rear, put giant bag in ski locker and fill that to tune the wake. Boat has a manual wake plate, so I will play with that as well. What do you think?


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Hi,

Given IF the GG sac is not a lot more expensive than the option to put a smaller sac up there I would go for it.
You can, as you said, partially fill it to get the right wake shape.
I know there are different opinions / preferences out there but I would keep the wake plate (trim tab) all the way up. As long as you have enough ballast up front I wouldn't think the wake plate can do you any good. If you would be back-heavy it is another story.

The positive with getting the GG sac up front is that when you have 3 guys in the back seat + the 800 lbs plumbed ballast you could adjust the front sac to get the best possible wake. Or if you realize that you need to add a 545-750 lb bag on that back seat to use with a throw over board pump you would have the same amount of weight in your 21 DD as in my (22) SSV.

Mike

Is your rear storage locker fiberglass? My 99 has a black plastic tray. Planning to remove that, and build out a carpeted locker. Hoping to fit 400-800 lbs in it. Since it's right above the gas tank, I'll have to build some framing to hold the weight. Will post progress pics once it's underway.

Rear storage locker is fiberglass, and a part of the hull.


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