Axis Wakeboard Boat Forum

Last night I did some napkin math to come up with a weight stored in the bag. This to me would be best case scenario, as usually the bag drains water out. It isn't a whole lot. Usually takes about 30 seconds to fill it back up when I hit the switch to top it back off. Anyway, I wanted to know how much weight was actually in the 950lb bow bag that is under the seats. So I got a one gallon jug, measured out one gallon of water in the jug, traced the water line, and cut the top off at the one gallon mark. Last night, on the lake, I drained water out of the bow bag and measured the time it took to fill the one gallon jug. I did this three times and averaged the times for my drain time (5.3, 5.6, 5.7 seconds). The average time came out to be 5.53 seconds to drain one gallon of water. I then topped off the bag, waited for the the vent line to stop draining, and then timed the time it took to drain the whole bag. Now I know some water doesn't get drained and again we are doing the best to make sure the time lines up with water coming out of the pump...but for this the difference should be pretty negligible. It took 4 minutes and 24 seconds to drain the bow bag. That would convert to 4.4 minutes. So lets do some math....

GPM = 60/5.53 = 10.85

Gallons in bag = 10.85 * 4.4 = 47.74

Bow weight = 47.74 * 8.34 = 398.15



This was done on a 2016 A24; however I don't believe the A series bow is any different between the boats. If that is the case we should all be getting around the same weight. Does anyone know if the bows are vastly different?

I have the sumo bow bag in my A24. This weekend I will try to remember to time it until the cushions pop up and then continue until water spurts out the side. We can compare time but I'm pretty sure my 2015 will be the same as your 2016.


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There are A LOT of factors that go into filling and draining of a ballast system. I don't see anything wrong with your calculations though. I think the error would be to assume constant flow throughout the entire draining process. You'll lose pressure on the bag side of the pump as the bag drains which would slow flow rates. Maybe take time to fill the gallon at start of bag draining, middle then end. Plug that average back into your equation and you should get a closer figure.

Or maybe your calculation is right. ha (I got a D in Fluids lol) But I would hate to think a full 950 bag is only getting 400 lbs.

I agree with your statement; however, I don't think it will drastically change the calculations. Over the course of 4.5 minutes the variance in head pressure would only cause a delta of, what I would guess, is a few gallons tops. That would mean a difference of ~25 pounds. That is negligible. The bag is clearly MUCH larger than the space it sits in. I was most interested in the napkin math since that is a very close estimate to the actual space it is filling into. I wasn't looking for the absolute weight.

This started from the fact that I was very unimpressed with how little the bag was able to fill for the what you could get out of it. Follow that with the fact that every time I take off the bow bag starts to drain a little leaving me to constantly have to top it off. So I decided to order some POP bags for the bow. I did it before I did any math though...it was just a guess that the bag was between 300 and 400 lbs. In order to validate that the lead would equate to what the bag was already I did the listed math to see if I was in the ball park.

There is never a time where you won't want the bow bag filled. My new plan is to keep the lead in the bow. I am going to push more to the nose as well, which should add some "weight" to the bow on its own. Then use the PnP bow bag on top of the seats when we run a filed boat with people and full PnP in the stern.

I was told by Fly High a couple years ago that the front bag has a capacity of 950 lb's however, when placed under the seats in the constricted space of an A22 it would only be able to hold around 450 lb's. I believe this is why you see the pros with the bag up on top of the seats where it can be fully filled in an unrestricted space

Now I know I need those two 150 straightlines in bow so we could walk between and get that extra I need to lengthen the wave
Boy, my front950 bag seems to drain at full strength for quite some time , but I guess math is math, next year 2419 prop and the two 150's, then I can use people as ballast cause can't really do that now even at se a level with the 1235.. Just was hoping to keep that clean look of no sacks out showing