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CantRepeat 12-27-2012 07:28 PM

How-to: Doing through hull ballast pick ups.
So I figured I post a good how-to on through hull ballast pick ups.

1. Location:

Finding a good location for the through hull ballast pick up. You'll need to locate the pick up and the best way to do that is by measuring from a hard point of reference on the bottom of your boat. I would suggest using either the current engine water pick up or the through hull for your prop shaft. Both of these points are easy to find both inside and outside of the boat. When laying out the location keep in mind that you will need to clear any obstructions inside the boat as well. With this in mind I suggest you move far enough away from the center line that you will clear the motor and transmission.

Once you have this location on the bottom of the boat tape it off with masking tape. Now inside the boat you'll need to locate the same spot and mask it off as well. The tape keeps the gel coat and fiberglass from splintering too much.

Once you have it tape off get your shut off valve and check to make sure the location you have selected has enough room to clear the valve. Keep in mind that you will need to thread it onto the through hull so you'll need room to rotate the valve as well as operate the valve once install.

2. Drilling:

Once all the taping and clearance checking is done you'll need to start your drilling. Hold your hole saw up to the location you have pick on the bottom of the boat and then trace the outside of hole saw onto the tape.

The purpose of drawing the outline is so you can drill a pilot hole. DO NOT DRILL YOUR HOLE WITHOUT DOING A PILOT HOLE. Drill the pilot hole first using just a single small bit. Remove the bit from your drill and screw it back into the hole. With the drill bit back in the hole get back in the boat and double check that the location is still good and has the needed clearance for the shut off valve.

Here is a case in point:

The solid yellow dot represents the first pilot hole. I drilled the pilot hole and check for clearance in the boat. I found that I was too close to the oil pan and that I needed to move to the starboard side more. The issue is, if I would have used the hole saw with out first using a pilot hole I would have been unable to change the location of the through hull with out a very costly repair. Sure I'd have shown my sack by just winging it but I'd be looking at a $500 to $1000 repair. But since I only used a pilot bit I can move the pilot bit over(red dot) and recheck the clearance. By using a very small pilot bit I can move the final through location any where with in range of the size of the hole saw(the yellow ring). In my case that was about a half an inch. The final through hole is the red ring and the first pilot hole will be inside of it and not cause an issue.

Now that I have check the clearance I can complete the drilling with the hole saw.

You'll need to take a round file and chamfer the edges of both the top and bottom of the hole at a 45 degree angle. This will keep the gel coat and the fiber glass from cracking/splintering. Once you have completed this remove the tape and clean the area with some mineral spirits.

Also note in the photo above there was a little open space between hull and inner lamination. Note sure why it was like that but I filled it with 3M 4000 marine adhesive sealant and let it dry for night. In the morning I ran my hole saw back through it. You may or may not run into this.

3. Through Hull install:

The only thing left to do is install your through hull and connect your check valve. I used a 1 inch brass mushroom through hull I purchased from wakemakers. I also used 3M 4000 marine adhesive.

Coast guard requires metal check valves on any fitting below the water line.

Nothing left to do but enjoy your ballast system.

Good luck and please ask any questions or offer suggestions.

mikeg205 12-27-2012 10:12 PM

Nice post -Tim

clrussell 12-27-2012 10:37 PM

This will come in very handy shortly! Thanks!


JRW160 12-27-2012 11:55 PM

Good info. I would also add to wear some long sleeves and clothes you can throw away afterwards. I drilled mine out while my boat was on the trailer and ended up with fiberglass all over me and the floor around me. When I slid out from under the trailer in a short sleeved shirt, I ended up with fiberglass in my arm for a week or so.

CantRepeat 12-28-2012 03:06 PM


Originally Posted by mikeg205 (Post 898386)
Nice post -Tim

I'll have to edit it a few more times. I was pretty buzzed when I wrote it up. I've had all the photos on my computer since the beginning of this year and I finally have the time and motivation to start posting again. :D

Stefan 12-29-2012 04:06 AM

I'm already planning to upgrade my stock ballast system to chase away those winter blues, this comes in very handy...

Thanks Stefan

bturner2 12-29-2012 08:19 AM

Great post. I'll probably be doing a similar upgrade to my brother in law's 215 vrs this spring. Between this and the wiring post the installation should be much easier. Would be nice if both we in the same thread as a single "how to" post.

CantRepeat 12-29-2012 09:18 AM


Originally Posted by bturner2 (Post 898572)
Great post. I'll probably be doing a similar upgrade to my brother in law's 215 vrs this spring. Between this and the wiring post the installation should be much easier. Would be nice if both we in the same thread as a single "how to" post.

It's in there too. :D

KahunaCraft 12-29-2012 11:02 AM

Thanks CantRepeat, Great post.

mikeg205 12-29-2012 11:46 AM

Neat idea - :)

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