Partially Installed: Semiautomatic ballast system

So i started on it today, most of the day was spent at west marine and home depot getting the stuff together. I talked to a metal fabricator about making a bracket to mount the ballast puppy on and he said he'd do it for $30 and to just send him the specs. Since I won't be using the boat for a few weeks and i want to make sure the bracket is done right i'll probably mail him the specs and pictures of jeff's mount(in the link below, the inspiration for this whole project, we've pretty much got the same boat). I've gotten everything i need for the system except for the electrical wire and adaptors for the blue fat sac things to the hose. In the end i'm looking for around 1,850 lbs of water (2 350's and 2 550's).

All i got done today was tapping into the raw water system. Picture below. Hopefully if the weather is alright tomorrow i can start running the hose through the boat and getting the ball valves installed on each hose and the electrical run, then when i get the bracket for the pump i can just hook it up and test it out.

For JEFF LIND: What size aluminum plate did you use for the bracket. I'll probably e-mail you as well.

oops, here's the link to see what my guidance is, thanks jeff lind

http://messageboard.wakeworld.com/MB/discus/messages/3183/105071.html?1080149730

Tom:

Looks like your MC has the same indmar as my malibu. I was thinking about an automatic ballast for my locker sac. When you tap into the fresh water pump system, don't you worry about starving your motor of water?

Are you having to drill any holes in your hull to have water enter / leave the system, or is it all through the existing interfaces?

Tapping into the boats cooling system is ok, however if this is done the only time you can fill the ballast is when the boat is at idle, as any engine speed higher than that requires the full water supply of the engine's impeller. At idle these engines need a minimal amount of water, basically enough to keep the impeller wet, so taking 8 gpm from a system that is pulling 30 or 40 gpm isn't a big deal. Emptying can be done at any speed, as it just reintroduces the water to the cooling system.

Didn't have to drill any holes, it fills and empties through the raw water hose. Once i get it all finished and perfected i might drill a hole for a through hull pickup and put my cooling system back the way it was, it would only be 10 inches from the pump inlet so it wouldn't have any priming problems. My only issue with that is whether it would have trouble pumping water out with backpressure on the pumps due to the exit being under the boat.

I just don't understand the fear of drilling a hole for a thru hull fitting?!

It wasn't fear of drilling a hole for it, it was not wanting to drill it and then find out my plans for the system were messed up and it wouldn't work as i designed it. I'd rather spend a little longer making sure something would work than have a hole in my hull that i didn't need.

Filling at idle sounds lik an IMPORTANT tid-bit of information. Good tip.

Other pluses about using the raw water intake (instead of a thru-hull hole) to feed the ballast pump are:

1. The boat motor/impeller pulls the water up from under the hull and feeds the pump so the ballast pump doesn't have to do that work.

2. Since my ballast pump is a mounted a bit downhill from my raw water intake "tee" there is always water at the balast pump inlet, so no dry running at startup.

3. The system can be removed and there are no extra holes in the hull.

-Jeff

I've been using a system with 3 ballast pumps tapped in to the intake for two years. I don't think there is any need to worry about only filling at idle speed. I fill or drain my system at idle, at crusing speed, or with the engine off. The temp guage always stays normal. I turn on my pumps as soon as I drive the boat off the trailer and fill the sacs all the way to the riding spot. I have a few theories as to why you can fill above idle speed.

1- The engine pump is much bigger than the ballast pump. In a battle for water between the big pump and the little pump, the big pump will win. If either pump is going to starve, it will be the ballast pump. 2- When the boat is traveling at high speed, there is more water pressure available for both pumps due to water being forced into the thru hull scoop. 3- The engine pump is variable speed, it pumps more water at higher RPMs. Again, these are just my own theories. Don't do it if you don't feel comfortable on your own boat.

For draining, the water will pump out with the engine off. I was also concerned about backpressure when I built my system. But it will drain just fine.

Thanks Matt! Great first hand experience.
I'm installing a similar system right now too.

thanks for the info matt! very good to know

what about battery drain, do you have any problem filling with the engine off draining your battery, i figure if you don't have a problem with three pumps then i shouldn't with one

Battery drain is definitely a concern with three pumps. I think the Simer pumps draw something like 13 amps each. If I run all three pumps at the same time without the engine on, sometimes I can hear one or more of the pumps start to slow down a little. Sometimes one of the pumps might even stop completely while draining when the sac starts to get low on water. On the other hand, I've never had any trouble starting the engine after running the pumps. I do have a dual battery system on a A-B switch just in case, but I have never had to switch to the backup battery.

Having a second battery gives me peice of mind to run the pumps with or without the engine running. I know I can always switch to the other battery and start the boat. If I only had one battery, I would be more diligent about only running the pumps with the engine on.

My thinking is the same as Matt's. There is NO way a little 13AMP ballast pump is going to starve a 3x bigger impellor running directly off a 310hp engine. Fill your ballast whenever you want, idle, cruising, whatever. Your engine will get enough water to keep normal operating temp.

-Jeff