Mounting/sealing new rubrail

[sailingharry]

Some brief backround:


Saga 43, balsa cored hull, but top 8" or so is solid glass 1/4" thick. I can get access to the majority of the hull from inside. I intend to mount a rubrail on the uncored portion (about 4" down from the toerail). The rubrail will be a Barbour plastic product, #R1015, in white (about 2.5" high, and 1.25" thick), with a 1" stainless strip on top.


So some questions for the esteemed knowledge base.


* How far apart should the fasteners be? The closer they are, the less chance for sagging between fasteners, and more constrained it will be in temperature changes. I'm thinking 12", but might expand it to 16".


* How big should the fasteners be? I'm thinking 1/4" carriage bolts for those that I can get to the inside for nuts. For the 6 or 8 feet (total, both sides) where I can't get to the inside, I would substitute #14 flat head sheet metal screws.


* The biggest problem is sealing. Some thoughts.
-- This is 100% in uncored hull, so there would be no structural damage from leaks, a good thing (and why I'm not putting it 1 foot lower down where I'd rather have it). But I still don't want water inside my boat!
-- An ideal solution would be to put all fasteners through the rubrail, put a ring of caulk around the fastener, and then lift the entire thing in place (20 foot sections) -- but I think that would be a disaster!
-- I could possibly move along rubrail, drilling 4 or 5 feet in advance of the last bolt, and get enough flex to caulk each bolt.
-- For the carriage bolts, I could use a neoprene sealing washer (it's used in roofing -- a stainless washer with a neoprene side to it that is a tight fit over the bolt and when compressed seals even tighter) which wouldn't keep water out of the hole but would keep it out of the boat. That wouldn't work for the sheet metal screws, but those might be such a tight thread that they won't leak anyway.


Any thoughts would be greatly appreciated!

[Dsanduril]

We like MaineSail's butyl tape. And with that you could prep and do a whole section in one go, without risk of getting sealant all over. Read his article, do it right. Use a counter-sink bit to drill a bit of a chamfer on your holes - back side of the rub rail and in the hull. Put fasteners through rail. Put a "donut" of butyl around each fastener. That will hold the fasteners in place as well while you mount. When you mount the donut will get squeezed into the chamfers you drilled and form a nice, tight seal.

Even if you don't use butyl, consider the chamfer, it makes big difference regardless of sealant.

[Edit] Link to Marine How-To

[sailingharry]

Oh, I do like Maine's butyl, and have a few rolls here. Chamfer isn't really an issue here -- the back of the rubrail is concave, so there is over 1/8 gap where the bolts will go.


My concern is the execution. I intend to make a jig (probably 3 or 4, more likely!) to hold the rubrail as the exact location, and then drill through the rubrail and hull in a single shot. Then insert a bolt, and move to the next hole. I can do that dry, and then take it apart. But once I have a 20' chunk of plastic, with 20 bolts sticking out the side, can I lift that in place and get all the bolts to go through again? It's not heavy -- based on the shipping information, each stick will come in around 30 pounds -- but it is seriously awkward. Perhaps one person at each end, and a person working the bolts in as it is slowly bent around the hull?

[Dsanduril]

Hmmm, I'd have to play with it to see how much it flexs. I'd guess/try drilling 4-5 holes, then fitting the first 2-3 bolts to hold it in place. Then move down another jig dimension, leaving the last ~2 bolts in the previous section not installed. Hopefully that would keep you lined up well enough, while leaving enough flexibility to get the bolts in. But would all depend on the material, so would have to play with it. Could even put those last ~2 bolts in the rail with the butyl, but not put the nuts on them. Especially if doing this in the water buy a few extra bolts in case the loose ones go swimming

[sailingharry]

Until you reminded me of the Butyl, I'd been thinking of LifeCalk, and shuddering as I thought about how to get that caulk around each bolt with just an inch or two of clearance pulled away from the hull. The Butyl is massively easier -- I can take little pieces and work them in and squeeze them around the bolt and not make an unholy mess. So the thought of working them in progressively makes sense.

[jimbunyard]

Originally Posted by sailingharry

Some brief backround:


Saga 43, balsa cored hull, but top 8" or so is solid glass 1/4" thick. I can get access to the majority of the hull from inside. I intend to mount a rubrail on the uncored portion (about 4" down from the toerail). The rubrail will be a Barbour plastic product, #R1015, in white (about 2.5" high, and 1.25" thick), with a 1" stainless strip on top.


So some questions for the esteemed knowledge base.


* How far apart should the fasteners be? The closer they are, the less chance for sagging between fasteners, and more constrained it will be in temperature changes. I'm thinking 12", but might expand it to 16".


* How big should the fasteners be? I'm thinking 1/4" carriage bolts for those that I can get to the inside for nuts. For the 6 or 8 feet (total, both sides) where I can't get to the inside, I would substitute #14 flat head sheet metal screws.


* The biggest problem is sealing. Some thoughts.
-- This is 100% in uncored hull, so there would be no structural damage from leaks, a good thing (and why I'm not putting it 1 foot lower down where I'd rather have it). But I still don't want water inside my boat!
-- An ideal solution would be to put all fasteners through the rubrail, put a ring of caulk around the fastener, and then lift the entire thing in place (20 foot sections) -- but I think that would be a disaster!
-- I could possibly move along rubrail, drilling 4 or 5 feet in advance of the last bolt, and get enough flex to caulk each bolt.
-- For the carriage bolts, I could use a neoprene sealing washer (it's used in roofing -- a stainless washer with a neoprene side to it that is a tight fit over the bolt and when compressed seals even tighter) which wouldn't keep water out of the hole but would keep it out of the boat. That wouldn't work for the sheet metal screws, but those might be such a tight thread that they won't leak anyway.


Any thoughts would be greatly appreciated!

Not sure I understand your approach.

I've never installed a rub rail with greater than 6" fastener spacing, and all of those were of a 'lipped' or 'flanged' nature, where they were held in position by a protrusion of the hull in addition to the clamping of the fastener to the hull. I would take 8" as a maximum.

At 12" to 16" spacing I'd hope the rail doesn't get much rubbing, because it will soon get distorted if it does.

Going by the Barbour catalog, it doesn't seem the R1015 molding goes with any SS trim. Are you using some custom material or combination?

According to the catalog, the stock SS trim comes pre-drilled, so unless the spacing is customer specified, that will determine your fastener spacing, as well as your fastener diameter.

Without 100% perfect sealing, the full thread on typical carriage bolts will be an introduction to leaks. And how will you ensure that the proper tension is applied? The plastic the rail is made from is comparatively soft, proper torque is needed to get a good seal whilst avoiding distorting the rail.

Screws have the advantage here, as a properly sized, pilot-drilled hole (with sealant) will help keep water out, and one can see when the proper tension is applied.

While the rail is 'rigid', it's not rigid like 1/2" steel. It should be entirely possible to start at one end and use the rail itself as a drilling template, following the sheer of the hull, sealing and final fastening every few holes as you drill the next few.

Or you could predrill the entire length of the rail (if it doesn't come from the factory predrilled), counter-sinking the back if you want, and then use it as a template, again countersinking every few holes as you progress along the sheer.

[sailingharry]

Jim,


Lot's of good thoughts.


The material is perhaps stiffer than the material you have used. It is as stiff, or stiffer, than wood. I have yet to receive the order, but I discussed moving it locally with the vendor, and he says they routinely carry a 20' stick on top of a pickup -- where 5 or more feet will project out each end. I can make no indent with a finger nail or even pushing on it with a screwdriver -- my concern with carriage bolts is actually that it will be too hard for the square part to pull into the hole! It doesn't feel unlike the material a 5 gallon pail is made of.



I have been continuing to ponder the screw spacing, and am thinking that 9" might be good (and still allow the stainless cap to miss the carriage bolts).


You are right, there is no pre-made combination for a stainless cap. I was frustrated by that, and spent quite a bit of time on the phone with them. There are parts of 2-3 profiles that I want to use -- but none that are perfect. I would love the total profile to be thicker than this (1.25" for the plastic, plus another .25 or so for the stainless, and I'd rather have a 2" total profile). They make one that is thicker with a groove for the stainless, but it has a back that can't be bolted to a smooth hull. I have in hand a sample of the rubrail, a sample of 1.25" curved stainless, and a piece of 1" flat random metal. The 1.25 is too wide. The 1" fits nicely, but I'll have to carefully mount it to keep it centered.


The stainless comes drilled on 6" centers. I really don't want to go all the way through both -- among other things, I don't think the stainless fasteners are going to be anywhere big enough to hold the rubrail itself. I'm guessing the stainless will be #8 or #10, and I'll be using 1/4" for the rubrail. But I do have to make sure my rubrail spacing is compatible -- 12" and 6" allow to be centered between stainless fasteners, 9" allows for a 1.5" offset. If I go to a line of 1/4" holes through my hull every 6", I do start to worry a little about the structural integrity of the hull! LOL.


The material is not as rigid a a steel bar, but it is likely to be at least as rigid as a similarly sized piece of wood. Roughly a 2x3, so if I'm out 2 or 3 feet from the last fastener, I should be able to flex it out an inch or two.


I'm not sure what you mean on the screws versus the bolts, as far as determining when they are tight? The screw, you go in until you get good solid resistance. The carriage bolt, you tighten the nut until you get good sold resistance. My concern on the screws is the risk of very high shear loading (catch the rubrail over a dock, for instance), and pulling them out. A 1/4" diameter sheet metal screw in 1/4" fiberglass only gets about 2-3 threads engaged (if that). And with the carriage bolt, I think the force to pull the square into the plastic will be more than necessary for proper attachment!


I thought about predrilling it (it doesn't come drilled), but have about decided it will be just as easy to do on the boat. I'll be doing it in the water, and my marina has a floating dock he'll let me tie to, so the rail will be right around waist high -- really convenient. I'll mark the holes, maybe even center-punch them for guidance, and then drill through the rail and the hull in one pass. I expect minimal sag (as you indicated), so I'll make a jig that sits on the toerail and has the shape of the rubrail cut into it, and this will support the far end and then someplace near where I am drilling.


Thanks for the thoughts!


Harry