26 October 2009

SHOP: leakproof through bulkhead hose

In a previous post I have described a solution for a hydration system.
The water bladder sits under the deck, on a “shelf”, and the drinking hose sits in front of me on the deck.
In the Nordkapp LV the deck is lower and less space is available in the foredeck.
Water bottles positioned under the bungees on deck just don’t cut it as they often end up in the sea, especially in rougher conditions.
While on short trips carrying water on the PFD is a possible solution (small amount of water) in the heat of summer in Queensland a liter of water does not get you far.
Hydration in a subtropical locale is a serious consideration.
The water bladder could not go behind the seat (Valley makes sure that the rear cockpit bulkhead is tight against the seat) so the best solution was to place it in the day hatch.
I wanted a positive seal between the drinking hose of the hydration system and the bulkhead.
A simple hole that is just undersized drilled in the deck might not do the job: small amounts of water could still get through and wet items that are otherwise totally dry in a Valley hatch.

I decided to position the drinking hose to the left of the cockpit.
On the right hand side there is the day hatch cover and the outlet spigot for the electric bilge pump.

After drilling a smaller hole with a high speed drill (Dremel_ I use high speed or gel coat chipping can occur) I enlarged it to a slightly undersized dimension for the clear PVC water hose.
I placed an “O” ring on the hose that is slightly constrictive and let it sit on the hose for a while.
The “O” ring would create a small indent in the hose making sure it will really seal well.

I roughened up a circle on the gel coat around the hole, clear off the “O” ring, cleaned the surface with acetone and inserted a slightly greased up (mold release) hose and “O” ring hard against the gel coat.

roughened-up circle on gel coat; hose and "O" ring inserted
I mixed up a small quantity of West System epoxy 105 with 207 hardener (UV stabilized), added some tint (I didn’t like the pale yellow color) and thickened it with microfiber (for strength and workability).
With a toothpick I carefully covered the “O” ring creating a full encasement of the ring.
After curing it overnight I removed the hose (it released easily since it was greased up) and shaved away the excess epoxy to make a smooth “fitting”
epoxy still needs polishing
The “O” ring is now encased in the resin with the rubber surface against the PVC hose making it really leak proof.

PS MAR'10 For a much simpler solution that does not require epoxy Kiwibird managed to source just the right size rubber grommet.
It apppears that her solution is just as effective as mine.
If you can get hold of a grommet that fits the hose tightly I suggest to follow her set up.

The hose can still be slid in-out to shorten or lengthen it according to the paddler's needs.
The hose end inside the day hatch has a quick release coupling that came with the bladder so removing and filling up the bladder is a breeze.
The hose is usually stashed under the deck bungees and can be easily reached when needed for a drink.

After trying different solutions for a drinking system this one seems to address all the shortcomings of the other(*) systems.

* other systems that I tried:

-1) water bottle on deck: not enough water, fall off and hinder some paddle strokes.
-2) water bladder on PFD: if enough water in bladder for a day’s supply PFD becomes rather heavy on the shoulders. Also hinders rolling.
-3) water bladder in cockpit and drinking hose threaded through tunnel of spray deck: bad idea in case of wet exit (rough waters) and inevitably pain in the butt when forgetting to remove before landing :-)
PS: Kiwibird simplified the drink hose system by using a rubber fitting that needs no epoxy work; details here


  1. Dude you are the MASTER Modifier!!
    That's a great system.
    When did you do all, this recently?

  2. Stew, that's what happens when I have more interest in creativity than watching TV... :-)
    Having a critical eye for all things (some call it perfectionism) I often see shortcomings in a lot of equipment.
    Designs don't happen sitting behind a desk but while using things where problems/improvements become evident.
    On the other hand there are so called designers that are just happy to copy other's work.
    Of course I am not reinventing the wheel here but just perfecting small little glitches

  3. There's a thread that was referred to me by a friend on twitter, to whit: http://www.ukriversguidebook.co.uk/forum/viewtopic.php?f=4&t=55522&hilit=electric+pump
    And I kind of like the idea of a pump that automatically begins pumping, so that the boat is bailing itself while you are still setting up your re-entry...although with your switch outside of the cockpit this is easily accomplished too...
    How did you get so good with the epoxy? Trial and error? (Or was it a show you saw on TV? :D)

  4. Stew, there is a pump from Rule that has an floating switch so when the water in the cokpit becomes high enough it automatically switches on.
    There are also automatic models that periodically just switch on regardless of water levels.
    The fist one is good however if you invert the kayak (like for transport) you better remember to turn off the power supply or you end up with a flat battery.
    The second one is kind of annoying to have the pump come on for no reason and needless to say it flattens the battery pretty fast too.
    On the comment of epoxy: it's rather easy to work with, all you need is some patience and common sense. West System publications are very good in explainig the basic properties and capabilities of epoxy.
    So far I never had a "disaster" with epoxy... some rough results, but never a disaster :-)

  5. Well I am patient and have some common sense...I'm sure I could figure that out!
    Rule seems to be the pump company for kayaks.
    This will be an excellent project for when ice forms over the lake and I want to be close to my boat!
    Thanks for the info!

  6. Kristen G. emailed:
    Hello there, I've just discovered your blog, and am mighty impressed. I was searching for an answer to my hydration system to stop threading the hose up and under my skirt and PFD, and here you've created a superb solution.
    I was wondering whether you could answer a few questions for me--I would be extremely grateful!
    Having not used epoxies before, what do you mean by thickening the epoxy with microfibre?

    thank you for your comment.
    Working with epoxy is relatively easy: mix the two components to the right ratio (different brands, different ratio) and you have a liquid the consistency of honey (at high room temps).
    This "honey" is too runny to "shape it".
    Desirably you should have a consistency of peanut butter. To achieve that you have to add a filler. Fillers can be bought at the same place that you buy the epoxy (if the retailer has a good range of products). I like microfiber filler since it thickens up the epoxy and makes it stronger. I also add a bit of pigment to make the epoxy more UV resistant (exposure to the sun for long times degrades the epoxy).
    I work with epoxy because I laminate, repair and modify a lot of kayaks.
    If all you want to do is just the hose fitting, maybe a ready made product with inbuilt filler like JB Weld could be used. I am not sure how well JB Weld sticks to gel coat though.


Thank you for taking the time to comment.
Because of spam received from unwanted manufacturers/retailers all comments are now moderated. Allow a few days for your comment to appear when the operators of GnarlyDog News are on safari.