Simple questions, With a simple answer (i hope)

[Thegerman618]

I am about the start my ballast install in the coming weeks, and I am familiar with just about everything except one major aspect:

How tight do I get the Thru-Hull? I know its brass, so I don't want to strip the threads. Do I have to worry about a stress cracks from being to tight? Is it just a feel thing, hand tight with half a turn? I will use 5200 on the mushroom from the bottom, and also put some on the nut to prevent leaks as that has been what I have seen in the past. However, I have also heard that you seal it the bottom and hand tighten the nut until the 5200 cures then wrench the nut down? I may be over thinking this and taking a simple job and making it difficult. Any advice would be great.

[IDBoating]

What I did (short version). You need two people to do this properly.

* If you don't have the special wrench that allows you to tighten the fitting, find an open-end wrench that fits into the bore but won't rotate past the locking ears inside, and hold it with a pair of Vice-Grips.

* Find a wrench that fits the fitting nut. A very large (12-15 inch) Crescent wrench will do.

* Cut the hole, and chamfer the gelcoat edge.

* Put a heavy bead of 4200 (removable) or 5200 (removable with pain) on the hull side of the mushroom head. Be certain there are no air bubbles in the adhesive. More is better here, to a point.

* Press the fitting into the hole from the outside. Smear it around a bit to insure 100% coverage under the mushroom head. You will get very messy doing this. It's worth it.

* While the outside person continues to hold the fitting, the inside person uses the adhesive to fill all around between the fitting and the hull. Put the nozzle flat against the annular ring between the fitting and the hull and squeeze hard, forcing that volume to entirely fill with adhesive. Then make certain there's a solid (no air bubbles) bead above the fiberglass for the nut to seat into.

* Spin the nut onto the fitting, and down into the adhesive bead. Spin it until strongly finger-tight against the hull's inside surface, squishing the excess adhesive out. You will get very messy doing this. It's worth it.

* On the inside, wipe up any adhesive on the hex-shaped wrenching surface of the nut. Leave the rest of the adhesive in place for now.

* Both parties now employ their wrenches. The outside guy's job is to hold the fitting firm, preventing rotation. The inside guy's job is to tighten the nut, coordinating with the outside guy to spin the nut without spinning the fitting. It's OK if you spin the fitting a little, but try to minimize it.

* Tighten the nut until it's very firm, but not crushingly tight. You're not trying to significantly displace or compress the fiberglass, you're just trying to take the slack out of the threads+nut. Think of it this way: It should feel like you'd have to "mean it" to back off the nut, but not require a breaker bar.

* Additional adhesive probably squeezed out during the tightening process. That's a good thing, because it helps insure you have a solid ring of adhesive top, middle, and bottom. With the nut tightened, both sides can now wipe up all excess adhesive. There's no need to leave any excess... adhesive that you can see is not contributing to a better seal, it's just a messy glop. That said, I'm more particular about the outside than the inside. I like to leave just a thin visible white line between the gelcoat and the mushroom head.

* LEAVE IT ALONE until the adhesive fully cures. Don't hurry. Don't be impatient. Give it time to properly cure.

Also: If you're using especially large pumps, or a big manifold system, etc. it's a good idea to install a backing plate to distribute the stresses over a larger surface area than just the mushroom and nut. With backing plates, I install them first using fiber-reinforced two part epoxy, then install the fitting. I like aluminum for backing plates but some people use epoxy coated marine plywood, StarBoard, etc.

Good luck and report back... it's a great feeling when you do the job properly!

[chpthril]

I use my german torque wrench and set it to gootntight Seriously though. good a snug while the marine sealer is fresh. Once the sealer cures, its set and wont budge. I use a short pipe wrench, so it gives me decent leverage but not gorilla strength.

Sanding the edge of the whole to a bevel should prevent any cracking issues.

I use a non-permanent white marine sealer, more like the 3M 4200. I like to put a bead on the face of the thru-hull then a bead around the inside of the hull that the jam nut to bed into.

[Thegerman618]

Thanks for the info guys, "gootntight" I am familiar with this. Do you think I will need to use a backplate for 2 Attwoods (T1200's)? I don't suspect they weight more than a few ounces each, probably a little more once the hoses are attached. Should get started in March(ish) time frame I can stand to be outside for more than a few hours. Or till this el nino hits and leaves so I can put the tower back up and get out there.

[chpthril]

The pumps weigh 16 oz each. I dont see a need for the backing plate but would not discourage its use either.

[Thegerman618]

Thanks Chpthril, I don't think I am going to run the back plate as of now I got to keep the cost as low as possible for my initial startup. I will have to add on later, or as needed.

[IDBoating]

Backing plates don't cost much, and you won't put them in later. A piece of scrap 0.5" aluminum from a local metalshop or machine shop will be really cheap, heck they might even give it to you for free.

It's up to you whether you want to do it or not, but cost isn't a reason not to do it.

[chpthril]

If he asked, id bet his ballast suppler would toss in some scrap composite material to make a backing plate. It might even be OEM Tige material

[IDBoating]

If he asked, id bet his ballast suppler would toss in some scrap composite material to make a backing plate. It might even be OEM Tige material

x2!

[Thegerman618]

your the best Mike, if you wouldn't mind throwing some in. I will be out shaking the money tree in a week or so and ready to make the purchase.

[bluebomb78]

I chose to utilize a seacock when installing the thru hulls for my ballast system. It's a bit more expensive but, in my opinion, worth it. A reference that I found very useful:

http://www.pbase.com/mainecruising/seacock_primer

[IDBoating]

Yep, formal marine seacocks are superior, but most people don't want to spend the money or (especially) the time to properly install them. If you are willing, good on 'ya, mate!

[Thegerman618]

Those almost seem like over kill for fresh water boats. I understand the Home Depot/Lowes is not a marine store and their equipment is not designed for extreme applications, (Especially ocean/salt water applications). I would imagine that if you balance the pumps properly and ensure there is no torque from the pumps on the thru-hull in any direction, there is a slim chance of breaking the thru-hull. I kept a steel cap in my old boat for just this reason though, if it ever snapped I could thread the cap over the thru-hull to stop the leak. Thanks for the information.

[IDBoating]

Whatever hardware you decide to use, buy it from ChpThril on here. You'll be sure to get the correct stuff, no rotted out valves from him!

[Thegerman618]

Of course, Chpthril is the best! Thanks for all the help and information guys, I will post some pictures when I am done with the install.