|SJ23 Tech Tip B17, (2019-05-09) Bob Schimmel|
Cockpit Drains -
Transom Installation and Maintenance.
|Ever noticed water pooled at the bottom of the port cockpit locker and wondered
where it came from? Well there are several possible sources; cockpit thru-hull fittings, gudgeon bolt
holes, toe rail screw holes,
toe rail deck seal, transom moulding, water overflowing the port locker
lid gutter, scupper holes and a myriad of other minor things I haven't found
yet. The port locker gutter will overflow
on a long starboard tack if enough rain falls on the seat or if you throw a bucket of water on it.
There are better designs on other boats but you'll have to live with this
one, although many people have sealed their lid to solve this problem. If
water has filled the "sugar scoop", under the cockpit just behind
the aft cockpit bulkhead support, it's a sure bet that you have a leaky gudgeon
bolt hole, cockpit or transom thru-hull
fitting. On the other hand it could be something minor like the back
stay chain plate or the transom moulding. Either of these problems can take on a whole new
dimension if the leak goes beyond a dribble! This leak is not a problem to
shove to the back shelf while you idly sip your beer in the
example, an open thru-hull fitting can sink an SJ23 in about 10 minutes.
Not a lot
of time to do something about the problem is it? Since all of us
to the principle that prevention is better than cure, it is best to check
the integrity of the cockpit drainage system on an annual basis. NOW
would be a good time!
The cockpit sole of an SJ23 is sloped aft slightly so water and debris can flow to the drain holes, back into the "drink" where it belongs. This helps to keep the cockpit sole in front of the companionway cleaner, which does likewise for the cabin sole. In the original version of the SJ23, the factory installed the cockpit fittings directly above the hull fittings with a vertical vinyl tube connecting them a shown at right. This design is questionable as it is difficult to install the vinyl tube, check the hull fittings or seal them properly in the cramped space under the cockpit. I'm know the "little kid" in the shop was saddled with this job! How to do the cockpit crawl. Unfortunately, the port drain fittings are poorly aligned, which kinks the vinyl tube, creating a strained fitting and questionable seal. You can see the sealant separated from the hull at right. Its too bad this is such a poor photo. It is a difficult place to take one. I don't know when this fitting was last sealed. It looks original. In the later Mark I hulls and all the Mark II hulls the factory solved this problem by installing the drain holes through the transom as shown below. They are easier to install and alignment is relatively easy to achieve. In addition, the fittings will not be under stress as vibration of the hull is absorbed over the flex of the 1' long drain hose. This ensures that all seals stay water tight and you have peace of mind. There are other advantages for the transom location. Read on:
NOTE 1: To elaborate on point 2 above, (the most important reason of all) you should consider how easy is it to plug a thru-hull fitting if a hose or fitting were to break? I can tell you that it is next to impossible to shove a wood plug into a thru-hull fitting installed under the cockpit, especially if the boat has already started to sink. It is pretty well impossible to reach the fitting from the surface. What complicates the job is that you are working blind, searching over quite a big area to find the fitting. You can take warmth in the fact that you will improve your chances of finding the fitting if you jump in the water with plug and hammer in hand. Doesn't sound appealing does it? Plugging the hole from the inside isn't much better either. The tight confines in the locker may lead to your demise in the urgency of the moment while it fills with water! This will take only 5 minutes. I'll let you use your imagination here! On the other hand, with the thru-hull fitting at the bottom of the transom, it is much easier to reach down the outside to plug the hole, even with the hull half submerged. You can also monitor the plug while under way, putting your fears to rest. Don't have a tapered wood plug? Use her bathing suit!
NOTE 2: - Each thru-hull fitting is installed in a depression so the top of the fitting fits flush with the hull or the cockpit sole. This is a clever design that extends the full 1/4" thickness of the fibreglass right under the lip of the fitting, creating the strongest possible installation with minimal cost. The lock nut tightens against a full ring of fibreglass. The flush fitting also means the cockpit can drain drip dry and the water on the outside flows by smoothly.
CONSTRUCTION (2008) - The cockpit drain plumbing shown at right belongs to a Mark II SJ23. The factory used the same 1.5" Delrin thru-hull fittings throughout the entire production of the San Juan 23, 24, 7.7 & 28 hulls. Likely other models as well. The transom of this Mk II is reinforced with an angled half round of fibreglass and a short horizontal length of imbedded filler across the bottom to support the lower gudgeon. Together they restrict where the transom drain fitting can be installed. It would have been better to install a 3" wide horizontal filler to support the gudgeon. Then the thru-hull nut would have been supported for the full 3600.
What follows are the issues and requirements of each component of the cockpit drainage system, going from top to bottom. After all, "s__t" flows downhill! Also read the maintenance section at the bottom. There are some good points to note there.
The outside of a thru-hull fitting is equipped with a two opposing notches to facilitate install/removal with a tool. The fitting also has a cross pin to block things from slithering down! You can grip the notches with a tool fabricated from a 12" long length of (2 x 1/8)" flat iron. Cut the corners of the flat iron off at 450 so they fit into the notches and cut the end off to make room for the cross pin inside the fitting. Insert the tool into the flange till the bevelled corners rest in the two notches. Press the tool down firmly to prevent the fitting from turning as you spin the nut. A tool like this is the only sure way to guarantee that you won't break the fitting or ruin the seal as you spin the nut.
GUDGEON BOLTS - The
four bolts that you see at the bottom of the transom in the picture above
secure the bottom
gudgeon. You may as well reseal all of them while you are
under the cockpit! These bolts can take quite a beating
over the years and are likely the other source of your leaks.
They must "complain" like heck every time you "touch"
the bottom with the rudder!
It wouldn't hurt to soak the holes in epoxy to seal the
COCKPIT FITTING & ELBOW - Reuse your recessed cockpit fittings if they are in good condition. If it has even one tiny stress crack or is weather damaged, replace it. Fact is, if you think it will break when you hit it with a (2x4)" then it should definitely be replaced. Gene Adams has used a stainless steel sink basket as a replacement part for the cockpit fittings, claiming they hold up very well. Sink baskets are equipped with 1.5" pipe thread so you can screw on an ABS plumbing elbow. They are available at most any retail plumbing store, not your favourite chandler! The black elbow adapter shown above and to left is a standard ABS plumbing fitting, (1.5" MPT thread to barb) that is required to direct the drain 900 towards the transom, eliminating a sharp hose bend. To facilitate assembly of the two, cut the barbed end and 1/4" of thread off the cockpit fitting and file the end smooth. In the photo above very little of the barbed end was cut off the cockpit fitting. If all the barbs are cut off, leaving just the thread, then the elbow fitting will cover most of the thread and position the fitting a little higher for better flow. Dry fit all components in the drain system. Sanitize and seal the recessed holes in the cockpit sole. Position the fittings so the cross pin is aligned fore/aft. This should go a long way towards preventing debris from accumulating over the pin and plugging the fitting, similar to hair in a sink drain. See NOTE 2 below. Tighten each nut fairly snug, not further.
Sealant must ooze out all around the flange to ensure a water tight seal. Seal the thread with one layer of white Teflon tape and screw the elbow adapter on, pointing the barbed end to its respective fitting on the transom.
TRANSOM THRU-HULL FITTINGS - If you are careful in your measurements, you can position the height of the transom thru-hull fittings so
the hoses slope down slightly with the boat floating level. This lets them drip dry for winter storage, preventing ice damage, and prevent new "life forms" from taking hold inside.
This is easier said than done.
You can install your transom fittings two ways, each with its own advantage. The flush installation is quite simple to install and mechanically solid. The horizontal or angled installation is more complicated to install but offers better strain relief and drainage for the hoses. Installing horizontally, which is what I did, allows the hoses to drip dry to prevent ice damage for winter storage. Keep in mind that the hoses will always retain some water. It's just an issue of how much. If the water fills a hose to below halfway, ice will pop loose harmlessly. Filled beyond halfway, the ice will likely split the hose.
FLUSH INSTALLATION - The 150 sloped transom is hand laid fibreglass, 1/4" to 3/8" thick. The factory installed mushroom style or surface mount thru-hull fittings flush to the transom without the wedges as shown below. In the case of the Mark II hull shown above they were installed through a beefed up fibreglassed section of the transom, eliminating the need for a wood backing block. For the Clark version Mark I hulls, you might want to install a 1/2" thick piece of mahogany (or other solid wood) saturated in epoxy to add strength to the assembly. Taper the edges and round the corners. Use Sikaflex or butyl rubber between the block and the transom to transfer the stress uniformly and seal the hole. With a flush mount installation your fittings should be installed as low as possible so the hoses slope down to the fittings. Regardless of how low you install the fittings, the hoses will likely retain some water due to the slope of the fitting. Take heart, it may become the birth place of a new life form on this planet. Don't be surprised if they wave back at you when you drain the hoses for winter storage! The hoses should drain dry as the hull is hauled up the ramp, but they may also fill with rain water while stored on land!
HORIZONTAL or ANGLED INSTALLATION - The transom is hand laid fibreglass, 1/4" to 3/8" thick and sloped at about 150 from vertical. If you want the hoses to drip dry with the boat floating then fabricate two150 angle wedges to fit around each fitting, one inside and the other outside the transom as shown below. These wedges will position the thru-hull fitting horizontal through the sloped transom so it is inline with the hose. Buy a thru-hull fitting with at least 2 1/2" of thread so the nut can tighten on the wedges with thread to spare. The nut must engage full depth thread to achieve full loading strength. The wedges also replace the backing block that would normally be installed inside the hull for additional strength. You can machine wedges from UHMW plastic, pour epoxy into a mould, or shape them from wood saturated with epoxy. My wood mock up challenged my carpentry skills and I'm sure the epoxy in a mould would have been easier. Ultimately I made my wedges from 3" UHMW rod because the material is maintenance free and relatively easy to cut on a band saw. Support the UHMW rod in a groove cut into the side of a (2x4)". This keeps the rod from rolling while cutting and will probably save your fingers. As each pair of wedges are cut off, tape them together around the circumference, effectively making a hockey puck. The purpose of this is to create a flat top and bottom to make drilling the hole for the fitting easier. Simply drill through the "puck" using a hole saw in a drill press. Grip the puck with a strap wrench. Dry fit all the wedges through 3/8" plywood before you install anything on the boat. Drill the hole through the plywood at a 150 angle. This helps to confirm a perfect fit.
WEDGE ALIGNMENT - On the mock up plywood "transom" you can see both sides to achieve perfect alignment. Not so on the boat transom! To make a bullet proof alignment on the boat, glue the outside wedge on the fitting flange and let cure. This way you have only two wet seals to deal with during final assembly instead of three. Draw a longitudinal line (felt pen) along the top of the fitting from the end of the barbs, across the thread stopping at the inside of the wedge. Draw a similar line along the top and ends of the inside wedge. With these two lines you can align the inside wedge to the fitting, ensuring perfect alignment and a water tight, stress free connection on the transom.
DRILL the HOLE - Drill the hole horizontally through the transom to ensure a perfect fit. If you install a transom fitting equipped with a cross pin, then install it with the pin in the horizontal position. See Note 2 below. This should go a long way towards preventing debris from accumulating around the bottom of the pin and plugging the fitting, similar to hair in a sink drain. However, the best fitting is one that does not have a cross pin since you can drive a wood plug in it.
SEALANT - Use plenty of Sika-flex or butyl rubber between the fittings and the hull to create a water tight seal. Note all the locations in the diagram where sealant MUST be applied. A bit MUST ooze out all around as you tighten the nut. Tighten the nut just snug to prevent stripping the thread or squeezing all the sealant out. Smear a very light coat under the nut to lock it in place so you can sleep at night! DO NOT smear it on the thread as it will make it virtually impossible to remove later. Remember to mask the gel coat off to create a neat installation and wash off all excess with paper towel dampened with acetone immediately after assembly.
HOSE & CLAMPS - While black automotive radiator hose is
used on the boat above, I used clear polyurethane braid
reinforced hose (rated for a potable water pressure system) so you can see
if the hose is plugged or free. It has excellent weathering
characteristics; tearing, abrasion, radiation exposure, oil, grease, fuel,
and resists UV making it suitable for outdoor use. The clear tube also
passes light into the cavity
under the cockpit which is kind of useful. Having said that, the rubber hose meets all
safety and operational requirements as the inside is smooth so water
can flow easily, there being no internal support spring as required to
radiator return hose from collapsing. A corrugated hose will reduce flow by as much as 30%
so use a smooth hose. This hose is also UV proof.
It was at this point that I relaxed knowing that we had a fix
and the hull was sealed. It sure feels good when it
all comes together so nice. The fiber reinforced polyurethane
tubing was installed a few days later after the Sikaflex cured and the temperature
60C. With the help of a pot of hot water to soften the ends, the tubing slipped right over the barbed fittings without complaint. The hose clamps were tightened after the tubes cooled off. The electrical wiring was secured to its permanent hangers. At long last, good drainage.
PLUG THE HOLES THROUGH THE BOTTOM - Of course once you install the transom fittings you must seal the two holes through the bottom of the hull. It sort of defeats the purpose of this modification to leave them open! The Gougeon Brothers have developed a well documented technique for this type of repair. I used their version that involves building a stepped "fibreglass puck" the same size and shape to fit the flange of the factory thru-hull fitting. The puck was epoxied in the hole and since the outside face of my puck already has gel coat on it, this eliminates having to apply it later. The plugs I cut out of the transom were used as the inside stepped up portion of the puck. I formed the layers to machine fit the hole (for ~1/8" clearance) and epoxied them together. Let cure for a couple of days. Dry fit, roughen the surface of each hole, sanitize it and apply the epoxy.
In the Gougeon technique they recommend wetting all surfaces
with unthickened epoxy, let soak a minute, then wet with thickened epoxy. Twist the puck into the hole and temporarily hold it in place with a plastic
covered stick across the back of the hole. Drive a short screw through the
stick into the back of the puck. Wipe off the epoxy that will ooze out
around the puck. Ensure that the puck is fully saturated with wet epoxy at
the perimeter as you must have 100% coating/adhesion around the puck
for maximum strength and sealing. Once the epoxy has cured to the green
stage it is safe to remove the stick as it is time to apply the inside layers. Apply
several successive smaller layers of cloth saturated with epoxy on the
inside of the hull. Make the bottom layer of cloth (largest) about 5" in
diameter. These layers of cloth effectively clamp the puck in place. Five
layers should suffice. Smooth the outside of the puck flush to the hull with thickened
epoxy and apply bottom paint.
Since Panache was parked in the bush for the winter and I don't have access to commercial AC power for heat, I had to wait till a warm Spring day for the temperature to hit 200C. This is rare on the Canadian prairies. I used an underwater repair epoxy with the consistency of putty to stick the puck to the hull without mechanical support from the inside. This allowed me to do this job on my own. After mixing the A & B components I smeared it on the inside of the puck, covering all the surface. Then I twisted the puck in the hole till the epoxy oozed out, inside and outside. This was more difficult to do than I thought because it required a lot of force to ooze the slow flowing putty around the edge of the puck. I had to lay on my back and push and twist the puck in with my boot, with a sheet of paper over the puck to keep it clean. In hindsight an epoxy with the consistency of a paste might have been an easier job. However, once the puck sunk to full depth I scraped the excess epoxy off with a putty knife and smoothed the gap with finger tips. The epoxy that oozed out on the inside was also scraped smooth, being careful not to push the puck back out. Then I let the whole works harden for an hour till the epoxy cured. Shortly afterwards I sealed the inside with a layer of thickened epoxy as shown in the diagram above. This last application capped and locked the puck in place. Later I smoothed the outside of the puck flush to the hull with epoxy and applied a coat of bottom paint.
It is important that you follow the epoxy application instructions exactly. Preparation is everything. Get real religious about this. Inspect your work in each step. A good repair is the same colour as the rest of the hull (inside view) and the edges of all layers of cloth are fully encapsulated. Once cured the puck will withstand blows from a rubber hammer, something you should do to confirm the integrity of your work. If you don't trust your repair work then find someone else to do the work for you. A bad repair will find your boat at the bottom of the drink.
Launch the boat and check for leaks. Kinda
keep an eye open on the water line for awhile! If all of it
stays visible, THEN go drink your beer to celebrate!
There are zillions of boats that have sunk due to neglected maintenance. Fact is, it's actually quite easy to stop a boat from floating! You donít have to do anything. Just let your boat sit a few years and eventually it will find the bottom all on its own! According to statistics for every boat that sinks at sea, four go down in their slips, all for lack of maintenance. Pretty alarming isn't it?
So if you don't want to change the cockpit drain design then at least inspect the fittings, sealant, hoses and clamps for overall integrity. As a word of caution, a Delrin or plastic thru-hull fitting will become brittle with age so this is another good reason to inspect them on a regular basis and replace a weak one before it breaks.
To disassemble, loosen the nut and the hose clamps on the cockpit fitting, crack the sealant and lift it up out of the cockpit sole and hose. A difficult to release hose can be removed easier with a hose removal tool. You can generally remove the hose without damaging the barbs that a knife cut will. Clean all components and reinstall in the reverse order. Seal all fittings to the hull with Sikaflex. Replace the old hose with new clear polyurethane high pressure fiber reinforced hose. A new polyurethane hose can be persuaded to slip over a barbed fitting if you first soak the hose end in very hot water. This will make the polyurethane pliable, permitting a full depth fit over the barbs. Let the hose cool before you tighten the hose clamps. Tighten the clamps till the hose material just starts to swell out the holes, NOT any further. Some of it should ooze out all around to ensure a water tight seal. If you want to test the seals for water tightness, seal the bottom fitting with a rubber plug and fill the tube with water. Watch for several days!
_____________________________ SOME SAFETY NOTES ABOUT FITTINGS ___________________________
FLOATATION: Just in case you are thinking
of adding floatation to a 3000 lb. SJ23, it requires approximately 50 ft3
of air to hold the hull at the surface. Actually it is a bit less than that
but the extra buoyancy is helpful to support crew and cruising junk onboard.
Be careful about assuming the boat weighs only 3000 lbs. Many come in
higher than 3000 lbs. due to the skill of the guys at lay up time. Confirm
the weight on a
commercial truck scale. If you can split the floatation 50/50 between the
bow and stern and there is sufficient volume to install it then the boat
should float level, more or less. You could use air bladders or rigid foam.
There are problems with either of these, mainly access to the respective
bilges. One person suggested installing deflated air bags connected to a CO2
bottle. In the event that a sinking occurs open the valve and your
floatation is ready to assist you. It's a wise idea to test the bags on a regular
In practice though, a fibreglass hull rarely breaks to cause a sinking.
It is generally a thru-hull fitting or a hose that fails or a grounding
on rocks that grinds the material. Most
hulls can withstand quite an impact before they crack to cause a sinking.
Swamping the cockpit is probably a more common occurrence. This is why you should
sail with the hatch and companionway shut in rough weather. Many people will
drag an inflatable behind the boat. They have excellent floatation and stability.
If you absolutely have to be out there, then it is wise idea to wear a cold weather immersion suit,
plus a life jacket
or an inflatable PFD. Also, leave your float plan with somebody AND stick
to it. Regular position reports via the VHF wouldn't hurt
either. One would think that waiting it out in the restaurant or in a quiet
harbour would be the better part of valour. Better this than to make a
nuisance of yourself with Search and Rescue!
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