Index

Toe Rail, Scupper or Transom Moulding Leak.
INDEX - Toe Rail Maintenance, Deck Seal, Scuppers, Transom Moulding.

TOE RAIL MAINTENANCE - "First, determine where it leaks; toe rail screw, deck seal, or hull to deck seal.  Look inside while someone runs water on the suspect area.  If a toe rail screw leaks (drop of water hanging from it), remove it (one at a time) and seal the back of the head with black butyl rubber.  Plan to replace the toe rail screws because the ends of most long ones were broken off during the factory installation.  I guess it was cheaper and faster than installing the correct length!  Afterwards run a bead of Sikaflex 230 around the deck edge of the toe rail to restore the deck seal.  If the hull to deck joint leaks you can either live with a slow leak or remove the entire toe rail and seal under it with fresh butyl rubber."  Gene Adams.

• Sometimes a leak is really obvious after a bucket of water is dumped on the deck; like a toe rail screw that drips almost instantly and can easily be spotted with a bright flashlight.  Other times you will have to run a steady stream on water to reveal a slow leak.  The screws most affected are close to the shrouds where the hull undergoes the most strain.  These screws are generally easy to seal because the hole is so clean. 
• With a leak that is difficult to find, draw a horizontal chalk line on the cabin or settee wall below the suspected area.  Any water running down will pull the chalk away, marking the location of the leak.  This technique should identify a leaky toe rail screw or a leaky toe rail quite quickly.
• It can require diligent sleuth work to find the tell tale streak of a leak.  The streak of an old leak doesn't always show if the water is clean or the hull is clean. 
• Another technique is to attach a paper towel or sheet of printed paper to the cabin wall.  Make sure the top is stretched tight against the inside of the fibreglass hull to wick up dripping water.  The paper towel will show a wrinkle where the water ran down and the printed text will run down the sheet.
• If you have water in the settee bilge, place a paper towel at each end of the bilge and run water on the deck.  The towel with the tell tale wrinkle marks reveal where the leak is.  At least you will know from which end the water is leaking.  You could also draw a chalk line above the towel to save time.  Don't have running water?  Wait for the next rain.
• Remember that the windows, stanchions, chain plates, scuppers, anchor locker, gudgeons, cockpit through hull fittings, backstay chain plate or the transom moulding could also be the source of your leak.  Sorry about complicating the issue, but this is reality!
• More toe rail info is available in Tech Tip B26 under "strengthening the toe rail."

Below is Buddy Wright's boat during a 2021 overhaul.  He decided to reseal both toe rails by removing them and sealing with butyl tape.  Its a job for two people; one inside and one outside.  He never did apply the bead of sealant along the deck as the butyl tape did the job.  What oozed out was trimmed off as the screws were tightened.  The hardest part was accessing the nuts at the aft end of the starboard toe rail.  In the end he cut a 6" access hole through the aft end of the berth to reach those nuts.

TOE RAIL SCREWS & NUTS (1995) - The factory toe rail screws & nuts loosen with time.  This is a natural function of the daily heat/cool cycling and flexing of the hull.  Don't be surprised to find a few missing nuts.  My experience is that the screws at the maximum beam of the hull loosen the most.  I think this is because the keel mass is located here.  With the hull heeled over, the weight of the keel opposes the wind force from the mast, twisting the hull between the two opposing forces.  This has to stress the toe rail screws/nuts and sealant around the maximum beam.  "I'm sticking to this theory until someone finds a better idea!"  If a screw is loose it will leak.  "No theory here, just plain fact!"  If you allow the screws to stay loose you also stand a good chance of breaking the butyl rubber seal under the toe rail.  So if you like work, don't tighten the nuts!  If you don't like work then tighten the nuts every 2 years.   I was surprised to find that mine had loosened almost a full turn in 6 years, despite the fact that I installed nylock nuts.  I thought nylock nuts would be the final solution to this problem.  Answer is; NOPE, but they definitely slowed the process.  This is a boat after all that flexes all the time and therefore requires constant maintenance.  To reseal the screws/nuts follow these steps:

1. Remove the screw and sanitize the shank and bottom of the head with acetone.  Don't touch it afterwards.
2. Apply a cone of black butyl rubber under the head.  Make the cone about 60⁰ so it works itself deep into the hole.
3. Sink the screw into the hole using a screw driver and don't twist the screw.  This retains as much sealant in the hole as possible.
4. Have another person tighten the nut on the bottom, again to keep sealant in the hole. 
5. Tighten the nut till the head is pulled flush with the toe rail at which time butyl rubber will have oozed out all around the head which ensures a good seal.  See photo at right. 
6. At this point the washer should be pressed against the bottom of the fibreglass, otherwise the screw will work itself loose very quickly.  While gaps are not allowed you should also not over tighten the nuts.  All you need is a very snug nut.  Over tightening it will create bowing between the screws which is hard on the toe rail seal and the fibreglass hull. 
7. Tighten it once and DON'T touch it afterwards.
8. Two days later I rubbed the excess butyl off with my thumb.  No gooey mess on my finger and a water tight seal.

TOE RAIL DECK & HULL SEALS (2020) - The toe rail deck seal deserves annual scrutiny to keep the cabin dry.  This is the fillet of sealant on the deck adjacent to the toe rail.  It wears out from thermal flexing, foot traffic, water and the sun beating on the deck.  In 20202 Panache still had the factory application so it was time to do something about the leaks. 

1. Wash the toe rail and deck to remove crud.  Its surprising how much collects here.
2. To cut through the fillet push a sharp wood chisel along the edge of the toe rail, with the straight side of the chisel to the toe rail.  Hold the handle almost horizontal so the corner just skims over the gel coat.  Then cut through the bottom of the fillet by pushing the chisel flat alongside the toe rail, tipping it up ever so slightly so as not to gouge the gel coat.  Alternatively you could use a 90 degree wood carving knife to push it off in one stroke.  In either case you should end up with a clean deck/toe rail corner as in fig 1 below.  Sweep or vacuum the debris from the deck.  It would be real annoying if the wind blew this on the sticky sealant.
3. Sanitize the deck and inside corner with acetone.  Don't contaminate it with your "greasy" fingers.
4. Apply masking tape along the deck, 1/4" from the toe rail, and along the top of the rail flush with the inside edge. 
   PS: It is possible to apply one continuous bead without using masking tape, but you would have to remove all deck obstructions.  There aren't enough 4 letter words in the English language for me to try this, keeping in mind that the deck seal is in direct line of sight from the cockpit.
5. Cut the sealant nozzle to the desired bead size and apply a bead of Sikaflex or 3M5200 sealant along the edge of the toe rail, completely covering the area between the 2 runs of tape. 
6. Cut the end off a popsicle stick, making a razor sharp cut, and run it over the bead at 45⁰, flattening the sealant to the deck.  Or you could use a soapy finger.  The end result should be a fillet that tapers smoothly down to the deck.  See fig 2 below.
7. Remove the masking tape while the sealant is still wet.  This creates a smooth edge.  If you leave the tape on the deck, it will become part of the fillet!  Now that looks sloppy.
8. Don't step on it till the sealant has cured for 48 hrs.  As the fillet cures it will become a bit concave.
   PS:  I discovered that 3M5200 shrinks (pulls back) quite a bit so don't be afraid to apply a generous coat.  I may apply another bead over it next Spring.
9. Don't worry if it rains.  The sealant actually cures a bit quicker with water on it.
10. PS:  After a month of monitoring for leaks I can declare that the hull is bone dry again with a new deck seal.  Who would have thought the seal leaked that much since it still looked good.  We had some pretty goof rain here to fill the locker under the settee to 2" deep.  I never saw a trace of water running down the cabin wall.
11. Similarly reseal the hull side of the of the toe rail. 
    PS:  It would be very difficult to apply a straight bead with the boat floating.  For this reason I pulled Panache from the water a week early this Fall.  It is a tiring to scrape the joint clean, mask both sides then caulk the joint ever so carefully.  This is the reason it took all day.  See photos below.

SCUPPERS (2014-2016) - The scuppers are located mid ship at the lowest part of the deck to pass water under the toe rails and over the side when the boat is floating on her lines.  (Drilling drain holes through the bottom of the toe rails was not an option at the factory since the flat portion is 3/16" above deck height).  To those of you with scuppers lined with gel coat, consider yourself lucky not to have to deal with a leak into the cabin here.  I bought Panache in 1986 and have always known her to have sealant in the scuppers so I assumed other early hulls had sealant as well.  In Panache's case the water from the port scupper flowed into the cockpit locker and the port settee with a little bit flowing over the side.  Nothing that a sponge can't take care of but annoying none the less.  The water from the starboard scupper drained into the starboard berth and locker.  That was annoying because the cushion soaked up the water.  So if your scuppers are lined with marine caulking the rest of this narrative applies to you. 
NOTE - This explanation is a bit of long winded so read on if you want to learn from it.  I see no reason why somebody else should go through the same frustrations I did.  However, if you want to go directly to the solution, click here.

  2014 - While searching for my elusive deck leak I finally pin pointed it to the scuppers.  It was difficult to believe they leaked since the sealant inside looked and felt in excellent condition.  I checked it many times over the years and found it to be dry and absolutely smooth and tight.  But I still had water coming inside so one day I pointed my brightest flashlight inside a scupper, holding the light at the critical angle, and spotted an edge of sealant that was detached.  Is it ever difficult to see inside a flat black scupper.  With more poking I discovered NONE of the sealant was attached to the fibreglass.  In fact, there was a perfect sphere of cured sealant nestled in there, holding water behind it.  Much to my surprise I discovered three 1/4" holes at the back of each scupper that are a direct path for water to flow INTO the cabin.  I think these holes were created while forming the deck seal during manufacture.  With my upper galley cabinets covering the wall it was impossible to detect the water trickling inside.  My first sign of a leak was a damp cabinet, cushion bottom and a bit of water inside the settee. 

Subsequent repairs with Sikaflex lasted only a few months despite the fact that I cleaned with an acetone soaked rag.  Later I scrubbed it with a toothbrush and what flowed out were bits of light brown, caked stuff. Looking back on it the surface of the scupper must have had grunge on it, preventing the sealant from sticking.  I sealed it with Sikaflex.

  2015 Spring - Since each application of sealant eventually leaked, I decided to try butyl rubber with a 1/2" vinyl tube through the cavity.  The tube worked and most of the butyl rubber stuck but after only 6 months it too leaked.  Butyl rubber is too soft in the hot sun for this application so out it came.

  2015 Fall - Next I tried a three step approach to sealing the scuppers.  I sanitized the cavity then jammed Marine Goop into the back and allowed it to harden for 24 hours.  It sealed the scupper.  I had to seal the holes from the outside since it is impossible to access the scuppers from the inside.  The hull liner blocks access.  You would need some real skinny hands to reach in there.  Then I applied a light coat of DOW Betaseal U-418 urethane (quick cure, primer free adhesive for auto glass) to the surface and let it cure for 24 hours.  The gooey urethane showed real promise that it would stick.  The easiest way to coat the back of the scupper is with your finger.  Don't blame me if you walk around with a black finger for 3 days!  Thankfully acetone and soap will wash off the sealant while it is still wet. 

It rained that night which helped to cure urethane.  Then I inserted a 5/8" vinyl tube that made a tight fit through the deck hole and filled the remainder of the scupper with urethane.  The surface of the urethane was smoothed with plastic sandwich wrap.  In the days after this application it rained half a dozen times and the cabin stayed bone dry.  You can see the finished results at right.  Finally ..........dry!

• A tube through the scupper reduces the size of the gap and creates a snug fit at the deck to ensure the sealant should stick at the perimeter.  The water should flow through the tube and not break the adhesion loose.
• After the sealant hardens use a razor blade holder to trim the deck surface and the top of the tube flush.  Bevel the inside of the vinyl tube so the water drains quicker. 
• Similarly trim the hull side of the sealant flush.  Trim the tube about 1/2" out from the hull so the water pours into the air instead of running down the hull.  This prevents oxidized metal from creating a black stain.  The protruding tube should survive the beatings of daily boating. 

After a winter and better part of a wet summer I was convinced that a snug fitting vinyl tube through the scupper is key to solving my problem.  The finished installation is at right.  Water pouring from the protruding tube is from a light rain.  The top inside of the tube was bevelled to speed flow. 

Consider this:
- If a sealant is wrapped around something it tightens and seals as it cures.  The tighter it gets the better the seal.
- If a sealant adheres against or between two surfaces, it shrinks towards them and stays sealed. 
- If a sealant coats the inside of a sphere or a tube it pulls away from the wall and looses the seal as it shrinks while curing.  This is the reason why a sealant is the wrong material to solve this problem. 

The weather gods and my free time finally aligned late in the season to put Panache into dry dock to tackle this and some other problems.  The urethane "plugs" came out in one piece.  They were damp on the outside, confirming the source of the leak.  This time I decided to seal the holes inside the scuppers with PC-7 epoxy, which doesn't shrink.  A Dremel Tool with a ball grinder smoothed the bumps in the back and roughened the surface so the epoxy could key to it.  I blew the dust out and sanitized the inside with acetone.  Now I know what a dentist feels like!  Then I plugged the back of the scupper with PC-7 epoxy putty, pushing small amounts of it in every nook and cranny till it filled the "factory" holes back there to a reasonably smooth surface.  This I let it cure overnight under the heat of a trouble light.  Over the next two days I applied two subsequent coats of PC-7, keying them to the previous green epoxy to ensure a uniform bond.  Finally I used the ball grinder to remove some "pointy" things and applied a last fill to make the inside smooth.  The cabin has stayed dry for two weeks, enduring several days of drizzle and a week of 4" deep sloppy snow on the deck.  For some reason wet snow is a tough test.  No new water entered the hull since the winter tarp went on.  But the real test will happen next summer.
  Summer 2017 - The port cockpit locker and settee stayed dry over winter so I coated the inside of the scuppers with TUFF epoxy paint.  Shown at right is the first coat.  Its a bit flexible when cured so it should stick to create the required UV protection for the PC-7 epoxy.  I never did install another vinyl drain tube in the scuppers.  While I liked the way they prevented stains down the side of the hull, they were also a bit of a nuisance.  "Inside every rain droplet is a dust particle just begging to stick to something."  One thought that always bothered me was the possibility of water flowing from the port locker to the settee.  This could spell a lot of trouble in the structural integrity of the hull.  Well since the scuppers were sealed I can confirm that the port locker water stays there and the settees stay dry.

TRANSOM MOULDING (2010) - After you've sealed the toe rail and dried up the water below the cockpit you will likely be so full of confidence that you may as well repair the transom moulding.  It's the only portion of the deck seal left to do and the moulding is likely scratched or has gouges from foot traffic.  This moulding is a one piece section of fibreglass that creates a cosmetic finish trim across the top of the transom, joining the port and starboard toe rails.  Its primary function is to provide impact protection to the corner with a semi-tough trim.  

While the moulding is glued and sealed in place with butyl rubber, it can be removed in one piece if you cut it with a razor knife or a sharpened putty knife.  Look at the tools laying in the transom notch to see how many different ones I used.  Use extreme care because the moulding is rigid and prone to break.  It is no longer available as a factory part, so DON'T BREAK IT!  This is definitely a job where patience is a virtue.  There was very little sealant holding Panache's moulding and it had marine growth in the voids.  I'm still convinced that new life forms start in places like this!  The minimal sealant made for easy removal but the poor support allowed the moulding to move under foot, causing some flex damage that I repaired with WEST epoxy.  Shown above and below is the transom with the moulding removed.  That old butyl rubber is pretty ugly looking.  Remove it with a razor blade holder and acetone.

Once the moulding is removed fill any gouges with epoxy and coat the surface with epoxy blackened with a liberal amount of carbon graphite powder.  This powder does an excellent job of restoring the black finish and adds a considerable amount of scuff resistance.  A moulding coated with this stuff will likely last forever regardless of how much foot traffic it experiences, it's that hard and slippery.  You should be able to buy carbon graphite powder from a chandler or a boat fibreglass repair shop.

If you break the factory moulding or it is badly damaged there are a few alternatives.  Keep in mind that this moulding is mostly cosmetic, offers little structural support but does keep the water out of the joint.

1. Replace the moulding with a commercially available vinyl outside corner moulding.   New vinyl is usually thinner and therefore catches less dirt along the edge.  This may be a good quick fix if the moulding can stand up to ultraviolet light and the impact of foot traffic. 
2. If you really want the dirt to slide off the transom then you can fill the butt joint with epoxy and cover it with gel coat. I've seen this finish on other San Juans and it creates a very pleasing smooth effect on the transom.  However, the corner has no crush protection against foot traffic and it wouldn't hurt to set some screws (same spacing as the toe rail) through the fibreglass to fasten the deck to transom. 
3. Repair your broken moulding with epoxy blackened with carbon graphite powder to restore the dark finish.  This is not as difficult as it may seem as you can likely tape across the gaps of the broken sections and use the tape as a form to join the pieces of moulding.  I realize this cured epoxy may create a rough finish but that is what grinders, files and sandpaper are for!  The Gougeon Bros magazine "Epoxy Works" cover this technique and others in good detail. 

When gluing the repaired moulding to the transom make sure you fully coat the inside of the moulding with black Sikkens Sikaflex to eliminate voids for maximum support.  As usual, use masking tape along the edges to keep the rest of the deck clean.  Now don't step on it for 48 hours till the Sikaflex is cured. 
 

Return to Tech Tip Index. . . . . . . . . . . . . . . Have a Question?