need to install a cable gland

[paulga]

I've got TotalBoats flex epoxy, it is labeled as "thick enough not to drain out of bonded joints".

in this case is a thickener still necessary?

The ratio is very strict as to resin and hardner. You can add things like milled fiberglass, cabosil and various other thickners. Thickners are not part of the ratio. You add as much thickner as you need to make the epoxy the viscosity you want. Six10 is thickened epoxy. It mixes in the tube to save the step og adding thickner. It is for a different application than unthickened epoxy. It works fine but is more expensive and you don’t have a choice of what viscosity you want. I use it occasionally but normally just mix my own thickner into the epoxy so I get exactly what I want. I have probably 5 or so different thickners to choose from. Although mostly I use 404, I believe, which is for structural work.

 

[jbinbi]

the biggest bit in that set is #12 or 7/32", do you mean that is enough to pass the ethernet cable through?

I'm thinking to drill a 7/8" hole (it can be up to 1.25"). using a crimper to make ethernet connector is a new skill but I'd like to leave it for future.

No. You cannot pull the connector thru a cable clam (that doesn't mean it can't be on the cable, just that you don't feed it through the rubber grommet from the end. Explained below and in video). You want the cable to be a tight fit in the grommet. An enet cable is roughly 3/16" (I haven't measured, but it is certainly less than 1/4"). You want to drill a hole about 3/16 in the grommet. The hole in the boat can be a bit larger, say 1/4 to 3/8 if you put the connector on after.

The cable clams I use are split from outside edge into the center. So you pry them apart, then put the cable thru (with the connector on).

As said above in a great post by Shrew:
1. Mark where you want the hole for the cable to be. Then put the inside ring dentered over where that hole will be, and drill hole for the screw that holds the ring to the hull. Just one of the screws as Shrew said.
2. If you want to leave enet connector, assuming rj45, then drill about 3/4" hole in the boat. If connector is to be put on later, hole can be a bit larger than cable. Personally, I don't like making holes in my boat, so if I have to, the smaller the better. If you don't use a countersink bit or something to champher the edge, the outside glass will split. It will be covered by the rubber grommet, I am not sure if I would worry about it.
3. Put cable thru grommet, then through inside ring, through gasket that goes between inside ring that holds grommet and boat. Then into the boat.
4. Pull as much cable as you will need into the boat. You should not be able to easily pull cable once everything is tightened down!
5. Put any caulking you want onto gasket. Put against hull. Screw inside ring onto the hull. At this point, it should be somewhat secure.
6. As Shrew said, twist ring up so you can drill other holes for inside ring.
7. Screw down inside ring.
8. Screw on outside ring. This will compress the grommet and make the cable entry in the grommet waterproof.

I have only used Bluesea's cable clams, so the procedure explained above is for their products.

https://www.bluesea.com/resources/580/Cable_Clams_Video

Final note. It is relatively straightfoward to put an RJ45 onto a cable. There might be someone who has done this who you know. I would try to do this rather than making a hole in the boat 2 or 3x what it needs to be just for the cable.

Also, make sure you are purchasing enet cable rated for outdoor useage!

 

[paulga]

The pilot hole should be of the same length of the screw, so it looks to me the smallest #4 drill bit (7/64") matches the "shank" size.

if the installation is on a cored fiberglass wall exposed to weather, should this bit or the a larger bit be used (for the first hole, not redrill)? I remember @Flatswing said to drill 3/32" larger, that will be 13/64". all these drill bits have a cone shape, how to decide which one to use to reach the intended hole size?

A clearer look

 

[paulga]

yes, the hole on the rubber gland should be no larger than the cable thickness.

the cable with rj45 connector on requires a 5/8" hole to pass. I heard a twist drill of that size does not work well on fiberglass?

No. You cannot pull the connector thru a cable clam (that doesn't mean it can't be on the cable, just that you don't feed it through the rubber grommet from the end. Explained below and in video). You want the cable to be a tight fit in the grommet. An enet cable is roughly 3/16" (I haven't measured, but it is certainly less than 1/4"). You want to drill a hole about 3/16 in the grommet. The hole in the boat can be a bit larger, say 1/4 to 3/8 if you put the connector on after.

The cable clams I use are split from outside edge into the center. So you pry them apart, then put the cable thru (with the connector on).

As said above in a great post by Shrew:
1. Mark where you want the hole for the cable to be. Then put the inside ring dentered over where that hole will be, and drill hole for the screw that holds the ring to the hull. Just one of the screws as Shrew said.
2. If you want to leave enet connector, assuming rj45, then drill about 3/4" hole in the boat. If connector is to be put on later, hole can be a bit larger than cable. Personally, I don't like making holes in my boat, so if I have to, the smaller the better. If you don't use a countersink bit or something to champher the edge, the outside glass will split. It will be covered by the rubber grommet, I am not sure if I would worry about it.
3. Put cable thru grommet, then through inside ring, through gasket that goes between inside ring that holds grommet and boat. Then into the boat.
4. Pull as much cable as you will need into the boat. You should not be able to easily pull cable once everything is tightened down!
5. Put any caulking you want onto gasket. Put against hull. Screw inside ring onto the hull. At this point, it should be somewhat secure.
6. As Shrew said, twist ring up so you can drill other holes for inside ring.
7. Screw down inside ring.
8. Screw on outside ring. This will compress the grommet and make the cable entry in the grommet waterproof.

I have only used Bluesea's cable clams, so the procedure explained above is for their products.

https://www.bluesea.com/resources/580/Cable_Clams_Video

Final note. It is relatively straightfoward to put an RJ45 onto a cable. There might be someone who has done this who you know. I would try to do this rather than making a hole in the boat 2 or 3x what it needs to be just for the cable.

Also, make sure you are purchasing enet cable rated for outdoor useage!

 

[jbinbi]

yes, the hole on the rubber gland should be no larger than the cable thickness.

the cable with rj45 connector on requires a 5/8" hole to pass. I heard a twist drill of that size does not work well on fiberglass?

Probably would work, might be better to use a circular drill (lots of teeth on outside of 5/8" and hollow in the middle) or possibly a wood bit.

 

[paulga]

is this the right way to use the bit --
position the countersink slider so that the drill bit is the same length as the screw?
then select the bit whose thickness at the countersink slider matches the thickness of the screw shank?

sure, something like this maybe? https://www.amazon.com/dp/B08DZH7V9...p_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM

 

[Bmarler]

is this the right way to use the bit --
position the countersink slider so that the drill bit is the same length as the screw?
then select the bit whose thickness at the countersink slider matches the thickness of the screw shank?
View attachment 144890

yes, exactly. and try the fit on a test scrap of wood to be sure you have the countersink properly set.

 

[paulga]

the drill bit set has #4, 6, 8, 10, 12.
This matching bit is #4, or 7/64"
if I want to drill a larger hole (to fill epoxy, assuming weather exposed wall and a self-tapping screw), should I go up to the #6 or 8 size bit?

yes, exactly. and try the fit on a test scrap of wood to be sure you have the countersink properly set.

 

[Bmarler]

the drill bit set has #4, 6, 8, 10, 12.
This matching bit is #4, or 7/64"
if I want to drill a larger hole (to fill epoxy, assuming weather exposed wall and a self-tapping screw), should I go up to the #6 or 8 size bit?

If you’re going for the best strength and waterproofing, and you’re accurate with the hole placement, go to #10. Then fill completely with thickened epoxy. After cure, go back and re drill the tapered #4. That should give a nice wall of epoxy all the way around the screw and good holding for strength.
In fact, in that instance, after drilling on location with the taper bit, go in the same hole with a straight bit. Then you get a nice column of epoxy all the way to the tip, instead of a tapered column.
I think #10 hole size (clearance) would be 13/64 or thereabouts.
I thought the cable gland was in a protected area, but if you’re practicing best technique, this is a good time for it.
Remember, always do a practice hole to set your first screw so you can see how it sets. You don’t want to break a screw in your finished hole.
You’ll probably have extra epoxy when you mix, no harm in filling a couple of extra practice holes in some scrap wood to use for trying the finished size. Hope that makes sense.

 

[paulga]

Thanks for the explanation.

if we change the self-tapping screw to a 1/4" machine screw (nominal size) with washer/nut, keeping everything else the same. is the drill bit for the first hole going to be 1/4"?

If you’re going for the best strength and waterproofing, and you’re accurate with the hole placement, go to #10. Then fill completely with thickened epoxy. After cure, go back and re drill the tapered #4. That should give a nice wall of epoxy all the way around the screw and good holding for strength.
In fact, in that instance, after drilling on location with the taper bit, go in the same hole with a straight bit. Then you get a nice column of epoxy all the way to the tip, instead of a tapered column.
I think #10 hole size (clearance) would be 13/64 or thereabouts.
I thought the cable gland was in a protected area, but if you’re practicing best technique, this is a good time for it.
Remember, always do a practice hole to set your first screw so you can see how it sets. You don’t want to break a screw in your finished hole.
You’ll probably have extra epoxy when you mix, no harm in filling a couple of extra practice holes in some scrap wood to use for trying the finished size. Hope that makes sense.

 

[CharlieO.]

Yes, now just drill the holes.

 

[Bmarler]

Thanks for the explanation.

if we change the self-tapping screw to a 1/4" machine screw (nominal size) with washer/nut, keeping everything else the same. is the drill bit for the first hole going to be 1/4"?

Yes, I always use nominal size and go for accuracy. If those pilot holes are perfectly on location, it’s easier to keep everything accurate through the process.

 

[Comodave]

I always drill one hole and put in one screw and leave it just a bit loose and then drill the next hole and put the screw in. And so on, that way you get the screws lined up with the holes perfectly. I never mark all the holes and then drill all the holes, you can be off a bit that way.

 

[Datenight]

I always drill one hole and put in one screw and leave it just a bit loose and then drill the next hole and put the screw in. And so on, that way you get the screws lined up with the holes perfectly. I never mark all the holes and then drill all the holes, you can be off a bit that way.

That is the best advise so far on this thread.

Rob

 

[paulga]

Yes, I always use nominal size and go for accuracy. If those pilot holes are perfectly on location, it’s easier to keep everything accurate through the process.

This through put is what I plan to install on topside hull, about 10in below the rub rail, the inside position is on the cabin wall.

The machine screws look like 1/4". The screws will tighten against the supplied rubber gaskets, not the hull. In this case should the screw hole still be countersunk?

 

[Bmarler]

This through put is what I plan to install on topside hull, about 10in below the rub rail, the inside position is on the cabin wall.

The machine screws look like 1/4". The screws will tighten against the supplied rubber gaskets, not the hull. In this case should the screw hole still be countersunk?

View attachment 144903

Yes, but not a deep countersink. Just a little chamfer of the hole to keep it from chipping out the gel coat at the perimeter of the hole.

 

[Bmarler]

That is the best advise so far on this thread.

Rob

This was mentioned very early in the thread. And is still good advice.

 

[paulga]

Yes, but not a deep countersink. Just a little chamfer of the hole to keep it from chipping out the gel coat at the perimeter of the hole.

The rubber gasket will go directly on the hull. Is bed-it tape or tube type sealant supposed to go between the gasket and the through hull metal piece?

 

[TJM]

Just so you know, the tools shown in thread 63 are tapered and will not provide consistent diameters. They are made and sized for wood screws. Ex: your #6 drill / countersink combination is for a number 6 wood screw. The deeper you drill, the larger the holes size will be. The heavy twist and deep flute will PULL them into the hole, be careful.

 

[Datenight]

This was mentioned very early in the thread. And is still good advice.

Guess I missed it in all the noise.

Rob

 

[Bmarler]

The rubber gasket will go directly on the hull. Is bed-it tape or tube type sealant supposed to go between the gasket and the through hull metal piece?

don't put anything but the rubber gasket against the metal fitting. in fact, if the hull side is smooth and is solid fiberglass (no wood core) i might not use any bedding besides the gasket.

 

[paulga]

Yes, now just drill the holes.

the hole saws are still on the way.
I'll start after all tools are ready.

 

[paulga]

I'll snap a photo tomorrow. The topside has horizontal grooves.

The Wallace 22 Dt through hull fitting also comes with a gasket, but it has self-tapping screws instead of machine screws.





The installer drilled pilot holes with a straight twist bit, holding the fitting in place as a template. Then he applied tube sealant around the center hole, and applied extra sealant to cover the screw holes. I know he didn't care to chamfer the holes or introduce epoxy. If we focus on his exercise of the tube sealant, is the same technique also applicable to my installation that has machine screws instead?

don't put anything but the rubber gasket against the metal fitting. in fact, if the hull side is smooth and is solid fiberglass (no wood core) i might not use any bedding besides the gasket.

 

[Bmarler]

I'll snap a photo tomorrow. The topside has horizontal grooves.

The Wallace 22 Dt through hull fitting also comes with a gasket, but it has self-tapping screws instead of machine screws.

View attachment 144914

View attachment 144915

The installer drilled pilot holes with a straight twist bit, holding the fitting in place as a template. Then he applied tube sealant around the center hole, and applied extra sealant to cover the screw holes. I know he didn't care to chamfer the holes or introduce epoxy. If we focus on his exercise of the tube sealant, is the same technique also applicable to my installation that has machine screws instead?

View attachment 144916

View attachment 144917

View attachment 144918

Just because he did it that way doesn’t make it right. The edges of the hole should be sealed with epoxy to prevent water migration into the fiberglass.
It doesn’t take much extra time to do a better job. The wallas fitting is a little different as it has a balanced combustion air and exhaust pipe. It also looks like it has a fiber gasket for heat resistance.
In your case, with machine screws, I would make the holes, epoxy the edges, and since you have plank lines in the hull sides, use poly sealant on the boat to gasket interface.

 

[paulga]

does it have some requirement on the heat resistance of the sealant due to proximity to the hot exhaust? I can see the concentric circle design is for the exhaust pipe to not touch the metal fitting directly, so the metal plate should not be too hot?

Just because he did it that way doesn’t make it right. The edges of the hole should be sealed with epoxy to prevent water migration into the fiberglass.
It doesn’t take much extra time to do a better job. The wallas fitting is a little different as it has a balanced combustion air and exhaust pipe. It also looks like it has a fiber gasket for heat resistance.
In your case, with machine screws, I would make the holes, epoxy the edges, and since you have plank lines in the hull sides, use poly sealant on the boat to gasket interface.

 

[CharlieO.]

does it have some requirement on the heat resistance of the sealant due to proximity to the hot exhaust? I can see the concentric circle design is for the exhaust pipe to not touch the metal fitting directly, so the metal plate should not be too hot?

I would install the exhaust as to the manufacturer recommendation. If there is nothing about clearance recommendations I would drill the hole the same size as the inner diameter of the gasket.

 

[Bmarler]

does it have some requirement on the heat resistance of the sealant due to proximity to the hot exhaust? I can see the concentric circle design is for the exhaust pipe to not touch the metal fitting directly, so the metal plate should not be too hot?

Metal plate can get pretty warm, but not horrible. Just don’t put so much sealant on that it drools all over the fitting.

 

[paulga]

The hole is specified as 1.5 in

I would install the exhaust as to the manufacturer recommendation. If there is nothing about clearance recommendations I would drill the hole the same size as the inner diameter of the gasket.

 

[paulga]

I took the measurements today. The installation location is at port side closet in the salon




The exact through hole need to be further decided on. It's close to the fuel fill and an ER vents opening. How to know what are behind the panel before drilling?



leaving 10 in for the exhaust pipe to run down, the hole will still be within the smooth part. In this case, is there no need for sealant under the rubber gasket around the through hole and in the screw holes?

Just because he did it that way doesn’t make it right. The edges of the hole should be sealed with epoxy to prevent water migration into the fiberglass.
It doesn’t take much extra time to do a better job. The wallas fitting is a little different as it has a balanced combustion air and exhaust pipe. It also looks like it has a fiber gasket for heat resistance.
In your case, with machine screws, I would make the holes, epoxy the edges, and since you have plank lines in the hull sides, use poly sealant on the boat to gasket interface.