Installing Seacocks - Follow Up Info !!

[Ross]

looking closely at Mainesail's cutaway picture

I woyld think that only about four threads would get recut to the proper taper. The result would be an improvement but would not be equivilant to a true NPT.I like to use the hard wood clamp when I am hacksawing a piece that I don't want to mar.

 

[Ross]

looking closely at Mainesail's cutaway picture

I woyld think that only about four threads would get recut to the proper taper. The result would be an improvement but would not be equivilant to a true NPT.I like to use the hard wood clamp when I am hacksawing a piece that I don't want to mar.

 

[Tom S]

Mainesail - How old was that thru-hull

that split and leaked when it got hit by the alternator.When you removed it did it show any signed of 'de-zincifation' (if thats a word)?If I took a new bronze thru-hull from a chandlery put it on the hard surface and droped an alternator from 5 feet up I find it hard to believe that I would crack the thru hull. I get a feeling that the thru-hull was probably starting to get old and wear through a little. All the more reason not to remove anymore material off a thru-hull than necessary for cutting NPT threads.Unless you were really trying to save some money and purchase ball valves from Home Depot, a good quality marine Flanged seacock are not that much more. I saw a 1" Bronze Apollo Flanged seacock with Winterizing drain plug from Defender for $60

 

[Tom S]

Mainesail - How old was that thru-hull

that split and leaked when it got hit by the alternator.When you removed it did it show any signed of 'de-zincifation' (if thats a word)?If I took a new bronze thru-hull from a chandlery put it on the hard surface and droped an alternator from 5 feet up I find it hard to believe that I would crack the thru hull. I get a feeling that the thru-hull was probably starting to get old and wear through a little. All the more reason not to remove anymore material off a thru-hull than necessary for cutting NPT threads.Unless you were really trying to save some money and purchase ball valves from Home Depot, a good quality marine Flanged seacock are not that much more. I saw a 1" Bronze Apollo Flanged seacock with Winterizing drain plug from Defender for $60

 

[Maine Sail]

Tom,

Tom,The thru-hull was indeed old although not original as Catalina used to glass pipe nipples into the hull and this was a standard bronze thru-hull and not a pipe nipple. At the time I really didn't care, or have a digital camera, and just wanted it out of the boat so I really did not examine it too closely but nothing else on that boat was suffering from metal corrosion. Part of the problem was perhaps the height of the valve and hose barb. Who ever installed the thru-hull never cut it down to reduce the height then threaded a valve and a hose barb onto it as well. My guess is that the alternator hit it fairly high (more leverage). I was able to back the valve off once the boat was out of the water and that did not break it any further but I could not back the big nut off because the through hull threads had been damaged. I wound up having to use a 4" angle grinder to grind the mushroom head off the push the whole thing back into the boat..On another note I wanted to post some pricing and really ask why someone would go to such lengths to take a shortcut. All marine prices are from Hamilton Marine except the pipe threading die.1" Ridgid Pipe Die (just the die) $98.00 (see link below)1" Thru-hull fitting 15.99 (needed for either installation)1" Bronze Marine ball valve $29.99 (for valve to thru-hull installation only)1" Bronze "proper" seacock $51.99So to cut corners and thread a ball valve directly onto a thru-hull fitting but re-cut the threads the cost is: Thru-hull @ $15.99 + ball valve @ 29.99 + Die @ $98.00 ($98.00 is bare minimum and assumes you already have a ratcheting die handle to fit the die head).The total cost for all this is $143.98. Of course if you have more than one 1" thru-hull you can amortize the cost of the die across a few valves but if you have different sizes you'll need a die for each. Still in the end this is a much weaker design than a flanged seacock.To do it the "proper" way the cost is this: Thru-hull @ $15.99 + 1" seacock @ $51.99 + three bronze bolts w/ nuts and washers @ $3.76. The total parts cost for this installation is $71.74 or $72.74 LESS than installing a ball valve directly on a thru-hull and re-cutting the threads.Let's say for the sake of it we don't re-cut the threads. The total parts cost difference is still only $22.00 to do it the right way.So we spend tens of thousands of dollars on a boat and we're taking a short cut on something as important as a hole in the hull that could potentially sink your boat and we're arguing over a $22.00 price difference between a 1" bronze ball valve @$29.99 and a bronze seacock @ $51.99...Again you can do what you want with your boats I'll spend the extra $22.00 and sleep well.........

 

[Maine Sail]

Tom,

Tom,The thru-hull was indeed old although not original as Catalina used to glass pipe nipples into the hull and this was a standard bronze thru-hull and not a pipe nipple. At the time I really didn't care, or have a digital camera, and just wanted it out of the boat so I really did not examine it too closely but nothing else on that boat was suffering from metal corrosion. Part of the problem was perhaps the height of the valve and hose barb. Who ever installed the thru-hull never cut it down to reduce the height then threaded a valve and a hose barb onto it as well. My guess is that the alternator hit it fairly high (more leverage). I was able to back the valve off once the boat was out of the water and that did not break it any further but I could not back the big nut off because the through hull threads had been damaged. I wound up having to use a 4" angle grinder to grind the mushroom head off the push the whole thing back into the boat..On another note I wanted to post some pricing and really ask why someone would go to such lengths to take a shortcut. All marine prices are from Hamilton Marine except the pipe threading die.1" Ridgid Pipe Die (just the die) $98.00 (see link below)1" Thru-hull fitting 15.99 (needed for either installation)1" Bronze Marine ball valve $29.99 (for valve to thru-hull installation only)1" Bronze "proper" seacock $51.99So to cut corners and thread a ball valve directly onto a thru-hull fitting but re-cut the threads the cost is: Thru-hull @ $15.99 + ball valve @ 29.99 + Die @ $98.00 ($98.00 is bare minimum and assumes you already have a ratcheting die handle to fit the die head).The total cost for all this is $143.98. Of course if you have more than one 1" thru-hull you can amortize the cost of the die across a few valves but if you have different sizes you'll need a die for each. Still in the end this is a much weaker design than a flanged seacock.To do it the "proper" way the cost is this: Thru-hull @ $15.99 + 1" seacock @ $51.99 + three bronze bolts w/ nuts and washers @ $3.76. The total parts cost for this installation is $71.74 or $72.74 LESS than installing a ball valve directly on a thru-hull and re-cutting the threads.Let's say for the sake of it we don't re-cut the threads. The total parts cost difference is still only $22.00 to do it the right way.So we spend tens of thousands of dollars on a boat and we're taking a short cut on something as important as a hole in the hull that could potentially sink your boat and we're arguing over a $22.00 price difference between a 1" bronze ball valve @$29.99 and a bronze seacock @ $51.99...Again you can do what you want with your boats I'll spend the extra $22.00 and sleep well.........

 

[Ross]

Mainesail, Very well said.

They don't have a thumbs up emoticon so please take the will for the deed.

 

[Ross]

Mainesail, Very well said.

They don't have a thumbs up emoticon so please take the will for the deed.

 

[RobG]

A different question...

Does anyone make a flanged through hull where the flange screws are covered by the mushroom? That would make the install so much easier without the need for filling, fairing and painting.

 

[RobG]

A different question...

Does anyone make a flanged through hull where the flange screws are covered by the mushroom? That would make the install so much easier without the need for filling, fairing and painting.

 

[Ross]

Since you install the thru hull and then the seacock

how would you get the bolts into the holes?

 

[Ross]

Since you install the thru hull and then the seacock

how would you get the bolts into the holes?

 

[Maine Sail]

Ross..

The seacock is installed first and through bolted. The thru-hull is then gooped up and threaded up into the boat. I think the reason for the bolts not being under the flange of the thru-hull are;1) to distribute the load over a larger surface area 2) Because most seacocks are sized for at least 5/16 machine screws. The heads on bronze machine screws are just about as wide as the flange of the thru-hull 3) It could be a safety measure to make sure they get filled and faired over properly and not just covered with marine sealant.There is an alternate method that allows you to avoid through bolting and that is drilling and tapping the backing plate. While not as strong it can be done. I would not advise drilling and tapping wooden backing plates unless you over drill and "pot" the holes with epoxy first. Obviously a nice thick fiberglass backing plate would be more durable to tap into.Heck even just a seacock wood screwed to the backing plate is going to be far stronger than a ball valve screwed directly to a thru-hull. Of course if you've actually decided to do it the right way why cut a corner and use wood screws?Most every quality builder here in Maine eg: Hinckley, Morris, Lyman Morse, Sabre all through bolt. Honestly it took me less than a half hours time, with 3M vinyl ester Premium Filler, to fill and fair the bolt heads on five new seacocks.....One caveat to through bolting is this; Make sure your hull is thick enough to recess the machine screw heads while still allowing enough strength. If your hull is not thick enough a solid fiberglass backing plate firmly epoxied to the hull is going to be needed! If your hull is too thin, and you countersink with wood backing plates, you've just defeated the whole purpose of through bolting and would have been better off just tapping the backing plate..

 

[Maine Sail]

Ross..

The seacock is installed first and through bolted. The thru-hull is then gooped up and threaded up into the boat. I think the reason for the bolts not being under the flange of the thru-hull are;1) to distribute the load over a larger surface area 2) Because most seacocks are sized for at least 5/16 machine screws. The heads on bronze machine screws are just about as wide as the flange of the thru-hull 3) It could be a safety measure to make sure they get filled and faired over properly and not just covered with marine sealant.There is an alternate method that allows you to avoid through bolting and that is drilling and tapping the backing plate. While not as strong it can be done. I would not advise drilling and tapping wooden backing plates unless you over drill and "pot" the holes with epoxy first. Obviously a nice thick fiberglass backing plate would be more durable to tap into.Heck even just a seacock wood screwed to the backing plate is going to be far stronger than a ball valve screwed directly to a thru-hull. Of course if you've actually decided to do it the right way why cut a corner and use wood screws?Most every quality builder here in Maine eg: Hinckley, Morris, Lyman Morse, Sabre all through bolt. Honestly it took me less than a half hours time, with 3M vinyl ester Premium Filler, to fill and fair the bolt heads on five new seacocks.....One caveat to through bolting is this; Make sure your hull is thick enough to recess the machine screw heads while still allowing enough strength. If your hull is not thick enough a solid fiberglass backing plate firmly epoxied to the hull is going to be needed! If your hull is too thin, and you countersink with wood backing plates, you've just defeated the whole purpose of through bolting and would have been better off just tapping the backing plate..

 

[Ross]

Mainesail , How do you avoid spinning the sealant out of the

joint as you screw in the thru-hull? I have always inserted the threaded fastener, well doped up into the hole and held it fast while I had the washer and nut tightened from the dry side. I would presume the same approach with a thru-hull . Dry fit everything and drill the bolt holes, take it apart and apply the sealants, install the thru-hull and screw the seacock down tight , align the holes and install the bolts and tighten the nuts. In that way you need only to move the thru-hull flange less then 1/3 turn to align the bolt holes.With a thin hull carriage bolts are an option. They won't stick out more than the mushroom flange of the thru-hull.

 

[Ross]

Mainesail , How do you avoid spinning the sealant out of the

joint as you screw in the thru-hull? I have always inserted the threaded fastener, well doped up into the hole and held it fast while I had the washer and nut tightened from the dry side. I would presume the same approach with a thru-hull . Dry fit everything and drill the bolt holes, take it apart and apply the sealants, install the thru-hull and screw the seacock down tight , align the holes and install the bolts and tighten the nuts. In that way you need only to move the thru-hull flange less then 1/3 turn to align the bolt holes.With a thin hull carriage bolts are an option. They won't stick out more than the mushroom flange of the thru-hull.

 

[Maine Sail]

You put..

Ross,You just put lots of sealant so the more you tighten the more it compresses, force fills the gap and squeezes out. I put a considerable amount of torque on my thru-hulls, with the step wrench, and right up to the end sealant is still oozing out. The head of a thru-hull fitting is not flat and looks more like the cross section of a dinner plate so it will hold enough sealant to make a seal. Doing it the opposite way you will still have to twist some as you can not make the final adjustment, of tightness with out the step wrench, because the bolt holes will not allow a final tightening. The final tightening of a thru-hull fitting into a seacock is always done from the outside after the seacock has been installed. I've owned a LOT of boats, I'm sort of a boat flipping junkie, and have done a lot of seacock retrofits and have never had one leak. I actually had the chance to pull one apart that I had installed. I did this because I wanted to up size the sink drain from 3/4 to 1" and everything inside was bone dry...Many high end builders, such as Morris, don't even use thru-hulls. They simply through-bolt the seacock to a finished hole. By finished I mean the interior of a hole is finished in gelcoat. This gives the hull the ultimate in a fair bottom. A properly installed seacock can work without a thru-hull and be water tight but a thru-hull gives you an extra measure or "double" security against water ingress and an overall larger margin of safety strength wise.There is tons of good discussion in this thread. I never imagined all the thinking and questions it would create...

 

[Maine Sail]

You put..

Ross,You just put lots of sealant so the more you tighten the more it compresses, force fills the gap and squeezes out. I put a considerable amount of torque on my thru-hulls, with the step wrench, and right up to the end sealant is still oozing out. The head of a thru-hull fitting is not flat and looks more like the cross section of a dinner plate so it will hold enough sealant to make a seal. Doing it the opposite way you will still have to twist some as you can not make the final adjustment, of tightness with out the step wrench, because the bolt holes will not allow a final tightening. The final tightening of a thru-hull fitting into a seacock is always done from the outside after the seacock has been installed. I've owned a LOT of boats, I'm sort of a boat flipping junkie, and have done a lot of seacock retrofits and have never had one leak. I actually had the chance to pull one apart that I had installed. I did this because I wanted to up size the sink drain from 3/4 to 1" and everything inside was bone dry...Many high end builders, such as Morris, don't even use thru-hulls. They simply through-bolt the seacock to a finished hole. By finished I mean the interior of a hole is finished in gelcoat. This gives the hull the ultimate in a fair bottom. A properly installed seacock can work without a thru-hull and be water tight but a thru-hull gives you an extra measure or "double" security against water ingress and an overall larger margin of safety strength wise.There is tons of good discussion in this thread. I never imagined all the thinking and questions it would create...

 

[Maine Sail]

You put..

Ross,You just put lots of sealant so the more you tighten the more it compresses, force fills the gap and squeezes out. I put a considerable amount of torque on my thru-hulls, with the step wrench, and right up to the end sealant is still oozing out. The head of a thru-hull fitting is not flat and looks more like the cross section of a dinner plate so it will hold enough sealant to make a seal. Doing it the opposite way you will still have to twist some as you can not make the final adjustment, of tightness with out the step wrench, because the bolt holes will not allow a final tightening. The final tightening of a thru-hull fitting into a seacock is done from the outside after the seacock has been installed. I've owned a LOT of boats, I'm sort of a boat flipping junkie, and have done a lot of seacock retrofits and have never had one leak. I actually had the chance to pull one apart that I had installed. I did this because I wanted to up size the sink drain from 3/4 to 1" and everything inside was bone dry...Many high end builders, such as Morris, don't even use thru-hulls. They simply through-bolt the seacock to a finished hole. By finished I mean the interior of a hole is finished in gelcoat. This gives the hull the ultimate in a fair bottom. A properly installed seacock can work without a thru-hull and be water tight but a thru-hull gives you an extra measure or "double" security against water ingress and an overall larger margin of safety strength wise.There is tons of good discussion in this thread. I never imagined all the thinking and questions it would create...

 

[Maine Sail]

You put..

Ross,You just put lots of sealant so the more you tighten the more it compresses, force fills the gap and squeezes out. I put a considerable amount of torque on my thru-hulls, with the step wrench, and right up to the end sealant is still oozing out. The head of a thru-hull fitting is not flat and looks more like the cross section of a dinner plate so it will hold enough sealant to make a seal. Doing it the opposite way you will still have to twist some as you can not make the final adjustment, of tightness with out the step wrench, because the bolt holes will not allow a final tightening. The final tightening of a thru-hull fitting into a seacock is done from the outside after the seacock has been installed. I've owned a LOT of boats, I'm sort of a boat flipping junkie, and have done a lot of seacock retrofits and have never had one leak. I actually had the chance to pull one apart that I had installed. I did this because I wanted to up size the sink drain from 3/4 to 1" and everything inside was bone dry...Many high end builders, such as Morris, don't even use thru-hulls. They simply through-bolt the seacock to a finished hole. By finished I mean the interior of a hole is finished in gelcoat. This gives the hull the ultimate in a fair bottom. A properly installed seacock can work without a thru-hull and be water tight but a thru-hull gives you an extra measure or "double" security against water ingress and an overall larger margin of safety strength wise.There is tons of good discussion in this thread. I never imagined all the thinking and questions it would create...