Heavily Weighted (6500 lbs) Ballast - Engine Wear & Additional Maintenance

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Originally Posted by jnr4817

Interesting. My 2018 Mojo with 400 is loaded with 4780# ballast plus fuel and at least 2 adults every trip. I’ve got oj945 prop, 500 feet elevation. At 11.0 it’s 3600 and 11.6 it’s 4200, I aim for 10* pitch.

@hayden what custom ballast did you install?

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I just got home from lake. I over estimated my rpms.
11.0 is 3200 and 11.6 is 3600.

Partial crosspost here but it's related to safety/durability so I believe it's worthwhile:

I missed this in the user manual (is it in there??) but from this point on, I will always have engine at 2k rpm when filling or draining G6 ballast. When running heavily weighted, your fill times bump up to almost double, you need the alternator to be 100% assisting with this. (I would occasionally, just run the boat to middle of lake and fill while at only 700 rpm (idle). I don't think you can do it like that, has to be higher ie. 2000 rpm.)

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Originally Posted by Hayden

Partial crosspost here but it's related to safety/durability so I believe it's worthwhile:

I missed this in the user manual (is it in there??) but from this point on, I will always have engine at 2k rpm when filling or draining G6 ballast. When running heavily weighted, your fill times bump up to almost double, you need the alternator to be 100% assisting with this. (I would occasionally, just run the boat to middle of lake and fill while at only 700 rpm (idle). I don't think you can do it like that, has to be higher ie. 2000 rpm.)

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I have G6 pumps and fill mine floating at idle all the time. Have not had any issues. Does it say not to do that somewhere?

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Originally Posted by HFarr

I have G6 pumps and fill mine floating at idle all the time. Have not had any issues. Does it say not to do that somewhere?

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Same I never rev it up to fill or drain

I fill at idle no problem, but normally cruise slowly to drain.

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I also do it at idle only because I'm a bit weird about carbon monoxide. I noticed that if we only fill/Drain once and stay on the water longer the batteries are almost fully charged, but if we go out 2 3 times for an hour or so, the batteries are at 60% in the evening. These pumps drain a lot of juice, so it may make sense to rev it a bit depending on a situation. We typically blast music which probably doesn't help much.
Fo what's it worth, just my 2 cents

I didn't see it in the user manual but when I took the alternator in to my dealer, (who also sells other boat brands), he mentioned that the 2k rpm filling was standard practice for the MasterCraft dual battery boats. I don't know if that means it's in the MasterCraft manual or if it's just what my dealer is telling their MasterCraft buyers.

Another situation that occasionally happens for me personally; fill boat, 1 surfer (me) 20-30min session, drain boat. If I'm doing that consecutive times a week, I'm thinking it might not be getting enough recharge time in between.

The alternators in these boats are 200 or 240a. 6 ballast puppies pull about 75 amps or less so it's really not that big of a draw on the alternator. They should be producing 100a at idle easily enough.
SC just wants the engine running because 75a for 10 min is a pretty hefty draw on the batteries if no alternator to recharge.

At 2k you'll be getting the full 200a output so there will be no draw on the battery at all so technically it's better but it's not necessary IMO.

Gotcha, if that's the case then I don't need to be as vigilant with it.

Agree with above, but its ALWAYS a good idea to fill and drain while the motor is running. The pumps draw power and why chance it.