previous discussions about Mk III Self-Rescue
- some serious, some less so -
featuring Andrew Haill and Richard Johnson

----- Original Message -----
Sent: Sunday, December 21, 2008 10:20 PM
Subject: W mkIII

Good evening and Happy  Holidays.  I hope you will have some time off during the holidays and not be in shut-down.

I’ve continued to turn this over in my mind.  The question that bothered me was how to make the penetrations in the hull, and how to secure the piping.
I looked at a number of fiberglass piping systems to see if they had a fiberglass stub-in.  They don’t seem to have an equivalent fitting so I’ve finally decided that a sch 5 or 10 stainless stub-in might make a good hull penetration.  It is interesting to note that the 4” stub in is nearly perfect in ID that is it has an Id of 4.33”.  The rule, assuming it refers to ID required that the ID of each be no more than 4.375.
My thought is this.  Drill the flange of the stub-in  in 6 places and through bolt it into the hull. It could be sealed with 3M 5200 or with a gasket.  I would probably go with the 3M.  Inside the  tank I would use PVC pipe and Fernco  rubber couplings.  The OD of the PVC pipe and the Stub-in is 4.5.  The standard Fernco 4” is designed for 4.5” diameter pipe.  Adjustments in height from the transom to the inside bulkhead near the floor could be made using PVC-DWV fittings.
So most of the part are available from the local plumbing shop. My local plumbing shop also caries sch 5 pipe and fitting in stainless steel.
I’d like your thought and see if you have come up with anything.  I know this seems a little nutty but I have worked with plastic pipe and Fernco couplings to know they make an airtight if not water tight seal.
Best Regards and hope to hear from you. 
Richard Johnson
From: Andrew Haill
Sent: Friday, March 28, 2008 8:55 PM
To: Johnson, Richard; Al Schonborn
Cc: dave /carol Hansman; Tony Krauss W4105 
Some thoughts below in red -cheers to all

----- Original Message -----
From: Johnson, Richard
To: Al Schonborn ; Andrew Haill
Cc: dave /carol Hansman
Sent: Friday, March 28, 2008 7:54 AM
Dear all,
I’m interested in reading all of this.  I’m afraid I will not be an early adopter but might be a close follower.

Another idea I considered, and most likely without merit, but an idea is this.  I found a company that makes a pourable two part closed cell foam that does not expand.   My thought was this.  Fill in the area in the rear tank which is lower than the floor with close cell foam to make the two level.  Finish the close cell foam with epoxy to seal.  Then make opening in the rear cockpit bulk head and the transom.  I would then add long air buoyancy bags for to aft, along the inside of the cockpit.  You lose some cockpit utility and when you cruise everything needs to be in dry bags.
This sounds like the final result might sort of approximate the Hartley W ... except they use permanent side floatation tanks and smaller holes.  I wouldn't do this nor recommend it... It would weaken the structure of the boat and wouldn't improve the self drainage if at all... in fact I think the boat would sink lower as air bags would tend to pull upwards away from the floor and would require greater depth of water to be effective than the fixed tank.  It would get water out fast once underway but would seem to me to have significant disadvantages, and is really serious and unnecessary surgery on the boat, not to mention not covered by the rules. 
My thought would be that upon righting the boat the water would automatically flow aft and I would hope out.  I would make the opening large enough that the water flow would be very fast. How fast? Good question.
As noted in my initial email I think the boat will only recover to the sink depth it would achieve if you got in and opened the floor bailers.... I kind of suspect this will result in about 4" of water in the boat .... and should be the depth eventually achieved after natural drainage of the likely higher post-capsize water level through the drain tubes.  But the head difference is very small and thus the driving force to drain relatively low.  The real advantage of stern drainage comes when the boat starts moving and some 'suction' effects start to come into play to remove the water.
A 4” round hole say 24” long offers a volume of 4.93 liters x 2 = 9.86 liters.  That would be the bottle neck.  The volume shouldn't much matter, it's the flow rate through the opening that should be most relevant... and one could jam a lot of water through two 4" dia holes.
  I guestimate that if you had 6” water in the cockpit you would have 424 liters of water also 424 kgs or 932lbs. ( 72” long x 60” x 6”)
Here’s where it get’s tricky and what keeps me awake at night.   To clear the boat of the water you need to slightly sink the transom. The water rushes aft furthing sinking the transom.  Will there be enough floating moment ( Sorry real engineers)  in the aft half of the boat to clear water. 
Not sure what you mean by clear the water.  I don't think you can clear the boat of water ... with you and crew in it and an open hole to the lake it can only recover to the equilibrium position as noted above.  That however should be less water than after the capsize which is anywhere up to a foot.  Say the back tank is 5' wide and 2' long.  Probably about 1.5' high.  Completely submerged that will provide about 940lb of buoyancy.   The advantage of the drain tubes comes in rapidly clearing the water once the boat is moving...  it usually takes some time to drain through the floor bailers once sailing.... stern tubes would just significantly decrease that by allowing the water to exit the boat quickly... not so much by gravity, but what would seem to me primarily the suction forces created by the boat motion.
My concern is that upon the initial slosh aft the back of the boat would sink and then a certain equilibrium achieved where no water would leave.   Any part of the boat that is out of the water is of no value in terms of lifting the partially sunk part.  
This would seem true whether a drainage tube exists or not.
If I were doing this as an experiment I would do the following.
On the average capsize with a boat that had air tanks in good working order, what is the volume of water in the boat, and therefore the weight.
Given this volume of water, and the top of the rear bulkhead as a limiting factor ( more than that the water sloshes over), where would the water reach in the cockpit?  In cross section the water would look like a triangle. 
Given this information you could determine the weight of water per linear inch of cockpit which would increase as the measurement moved aft.
The next question would be, what volume of air do you need to offset a liter, and therefore the total volume of water in the cockpit?
      a litre of air would displace a litre of water... but that is not presumably what you mean?
More importantly what is the volume of air in a MkII and where is it in the boat? Where is it in reference to where the water is in the cockpit?
 I would think that it would be important to match floatation volume to water volume and that the volume of air should have a positive lifting value versus the water in the cockpit.
If you could demonstrate that with the average or even worst case water volume in the cockpit, sloshed to the back of the cockpit, at max height, that there was a positive lifting energy ( sorry real scientists) versus the weight of the water, then you could argue that there would be a positive flow out of the cockpit. 
             Regardless of boat position there should only be positive water flow out of the boat if the level of the capsize water is higher than the boat would normally have with the bailers open...i.e. with empty MkIII boat and bailers water... Get in and wait and eventually you have what?  4" depth?.  Any water level higher than that after a capsize will want to flow naturally out of the boat... but the boat cannot completely drain no matter what static position you put it in.  The rationale for the stern tubes is not self drainage but get the boat moving and add the suction and dynamic effects that allow the bailers to work.  Big drain you have fast drainage.   That's how it seems it would work to me anyways.
 The good news is that once water began to flow that the ratio of weight to buoyancy would only get better.  Sounds like an excellent Calculus problem.  Unfortunately I’m a liberal arts major from Farmville Va.

I think until we can answer these questions or perhaps even more relevant questions posed by a real engineer or scientist, that any change to the boat would only be an educated guess.  This is why I hesitate to do anything.  I like the idea of the bailers, I think it would add to safety, I think it would work, but I think there are some fundamentals that need to be looked at first.
Kind Regards to all
Richard Johnson
That is quite an experiment and some pretty mean calculations.  I'll make only slight claim to being a real engineer and alas, I've forgotten most of the calculus that got me through engineering scholl (which for their continued reputation I will not name) but I'll take a stab at this.  I might have to make a few assumptions that will no doubt be appalling to the more learned but please bear with me (not to mention forgive).

 Firstly ....  the formula for drainage from a tank at atmospheric pressure (hopefully fairly safe to assume) is generally dictated by the following differential equation:
  to make things more difficult however the tank (cockpit) volume is also changing as we sink the stern, but if we consider it to primarily be triangular under the conditions described then it is clear that we can use the following:
  Secondly the rearward sloshing of the water can probably best be approximated by this graphical relationship

  Combining these two aspects, we can quickly see the water volumetric shape closely resembles the following
  A little bit of elementary calculus will help define the volumetric change rate of the cockpit water with time
 After expanding the formula with some turbulent fluid flow relationships primarily defined by:
  ... the next step clearly is substitution into the original differential equation for drainage, integrating, and solving for the resulting unknowns to easily provide the answer.  Rather than bore you with the final calculations, the results of this are probably best illustrated in pictorial form.

One more commonly sees another method of calculation utilized by those not so enamoured with the intricacies and joys of integral calculus.

PS ... the only part of this bs I even partly understand is the first equation... which actually is for drainage out of a tank.  Its amazing what Googling 'calculus equations' can come up with.  I doubt this adds much to the discussion but I had fun with it.  Enjoy.

From: Al Schonborn []
Sent: Thursday, March 27, 2008 10:56 PM
To: Andrew Haill
Cc: Johnson, Richard; dave /carol Hansman 
Hi, Andrew:
Too late for me to get into much tonight. You seem to have everything well in hand and nicely figured out. All in all, I can see no flaws in your reasoning anywhere, though I must confess that I'm surprised you had no trouble heaving to with a boat full of water. And, the way I get underway after sitting sideways to the wind with the board full up and the sails luffing, is to sheet the jib in gently until the boat (a) gathers way, and (b) bears away.
Good night for now.
Best regards,
Uncle Al  (W3854)
----- Original Message -----
From: Andrew Haill
Cc: Richard Johnson W10139 ; dave /carol Hansman
Sent: Thursday, March 27, 2008 10:04 PM
Hi Al /  Richard / Dave
my reply below in blue
hope all is well
----- Original Message -----
From: Al Schonborn
To: Andrew Haill
Cc: Richard Johnson W10139
Sent: Sunday, March 23, 2008 9:52 AM
Hi, Andrew:
Will post your thoughts in tonight's Weekly Whiffle. Perhaps that will bring forth further suggestions. Will do my usual comments in green below.
Take care,
Uncle Al  (W3854)
PS: Have copied Richard who should find your thoughts interesting and perhaps worth commenting on?
----- Original Message -----
From: Andrew Haill
Sent: Tuesday, March 18, 2008 9:44 PM
Interesting discussion in the latest Whiffle.  I had a conversation with Richard at the mid-Winters about this very topic.  Like him, I've been thinking of adding stern drainage in my boat although other projects and a difficulty in finding suitable fibreglass tube precluded it.  Perhaps this year.   It should work on any W version, but on the MkIII the floor is about the same level as the bottom of the transom so a drainage tube would be nicely horizontal.  The maximum size is identified under the rules as two tubes of nominal 4" size which should be quite enough and a big improvement over what can go out the floor bailers.
If the drain tubes can be level, that will be a big help. I didn't realize that they can be. It would be interesting to do some tests on such a system as you propose to do. I suppose that, in theory, the boat should drain itself once it is righted. The question would be how long this would take.
It wouldn't really matter... I'm not proposing to wait in the water for the boat to self-drain...  the advantage would be much faster drainage once sailing than achievable through the floor bailers (although I do think the water present after a capsize would tend to self drain to some extent even with the crew in the boat).   But with stern tube sailing drainage, one might not even need much use of the bucket because the water would go out pretty fast.
And then, the matter of climbing back into a high-floating Mk III with its lack of handholds, raises its ugly head -
especially for those of us who are not as spry as we used to be.   I went swimming off the CL at Hilton Beach in 2006 and had a heck of a time climbing back in, unlike in the wood boat where you can get a nice grip on the inside edge of the deck.
A non-issue.  The MkIII is not a CL16 ... see photo of my boat below... there is essentially as good a grip as in a wood boat or MkI... in any case one is usually scrambling in off the board as it rights and not directly from the water.
 And even so, I am still thinking off installing/bringing along a climbing aid - perhaps nothing as fancy as Tom Graefe's but something homemade as per the Chuck Jordan idea -  I like the wood one.  This would be a worthwhile safety thing to have permanently attached and accessible from the rear deck.  Wet clothing weighs a ton and make a mockery out of all that off season chin-up training when trying to get back in the boat from the water.
Many dinghies (regardless of floor bouyancy tanks) have stern bailers... they seem to work, and generally improve safety.  The goal particularly in cold or rough conditions is keep the crew out of the water and get the boat stable, dry, and sailing again asap.  Anything that gets the ice-cube water of Lake Superior out of the boat fast after the dreaded capsize would be a benefit.
The older I get, the more I'm inclined to believe in getting back into the re-righted boat a.s.a.p. rather than waiting for it to drain.   Not sure where the impression arose regarding waiting in the water for the boat to drain... that's not at all what I'm proposing.  I want out of the water and in the boat asap.  I do suspect stern drainagetubes will not only get some water draining out immediately (as discussed with the math in following paragraph), but by emptying the boat quickly with fast drainage once sailing there will be a lot less water sloshing about for a lot less time and much less possibility of recapsizing.   In short, back into the game and safer faster. 
I have the distinct feeling that by sitting both people well aft immediately after righting and bringing the board all the way up, the Scott Town-suggested method of just sailing away on a broad reach should work - and a pair of drain tubes would quickly remove any water that doesn't go out over the aft tank in the first forward surge. 
Without finding some tubing commercially, my plan was to make approx 4" dia fibreglass tubes by wrapping cloth around a piece of pipe as a mold.  Cut holes in transom and rear bulkhead, fibreglass the tube ends into those transom/ bulkhead holes, a bit of gel coat here and there, add shock corded transom flaps with a rubber gasket seal, and use a couple of 4" hand hole access ports on the rear bulkhead openings so the drainage tubes can be screwed shut and made watertight for sleeping in the boat.  Should just take a couple of hours. Ha.!
A MkIII with open bailers has a dry floor until you stand in it and water starts coming in.   It shouldn't sink too far before the bouyancy of the front and rear tanks provides equilibrium again ( the average 360lb crew would need only about 6cu.ft of additional displacement with water at 62lb/cu/ft).  Just the rear tank alone (at say 5ft width x 2ft length) provides that with a 8" submergence.  A test is needed... open the bailers... add the crew ... drink a beer and see just how much water comes in.  I'd guess the actual sinkage with open bailers should be less than the depth of water that frequently sloshes around after a capsize - meaning given half a chance some water might even drain out on its own accord.  Even if not, stern drainage tubes would get the water out far faster than the floor bailers once sailing and eliminate much of the instability that follows a capsize (the MkIII is particularly prone to this problem with all that water sitting on top of the under-floor bouyancy tank).   Looking at the pictures of the new Hartley W that Kit took in London, it would appear it has under-floor bouyancy too, so there shouldn't be too much difference between the drainage setup of the HW version and tubes installed on a MkIII.  In short, it should work.
I am in full agreement with Richard's observations on the sealing and rear hatch of the MkIII.  It leaks as he noted, and is difficult to achieve reliable bouyancy and maintain reasonable access.  Although the MkIII is generally a fine boat, this is one of a number of aspects that could easily have been done better.  My hatch modifications and some other items are listed somewhere in the WIT  (  I would suggest adding the righting line to anyone concerned about quick recovery and turtling issues.
I just re-read your W modifications article and am again impressed.  thanks.  The righting line sounds a fine addition.
The other thing I was pondering is whether one could fill the top of the mast with foam... say the expanding type used in home renovations.  There might not be much volume there, but even a few pounds of floatation force at the mast tip would be helpful in slowing the roll-over tendency.  Assuming a 2"dia mast section, about 3 feet of foam would provide 4lbs of bouyancy (the equivalent of a bag of sugar) at the mast end.  If an inner tube is sufficient (assuming it's not from a truck), a foam filled mast tip should be roughly equivalent.
What would you do about the main halyard getting past the foam? And how would you get the foam in there? Seems to me like the bicycle inner tube or Richard's pool noodle would be an easier option?
Easier but the asthetics suffer significantly.   As for the halyard passage problem,  one solution would be to fasten to the halyard end as thick piece of rope as will fit through the mast base entrance pulley.   Haul up to the mast head and tension.  Use a long tube to extend the foam can nozzle to reach down inside the mast from the top.   Insert foam as one extracts this filling tube from the mast.  When foam is essentially hardened pull the thick rope back out.  Voila, a larger diameter hole through the foam that the halyard passes through.  I'd probably refine this by wrapping the rope with some tape/plastic/ paper etc.,  to ease separation from the foam.    Having a bit of bouyancy at the mast would be a good thing -  and it being internal even better.
As for the sloshing water over the back tank theory.  Put me down as a bit skeptical.  That would require a significant sinking of the stern of the boat and as noted the bouyancy of the rear tank would seem to make this difficult.   Besides, a foot of water in a W weighs over a ton and makes it tough to gain much in the way of sudden motion. 
I don't imagine it would take much sudden forward motion to slop the worst of the water out? What I expect Scott pictured was for helm and crew to move well aft and at the same time sheet in and go - the water would rush aft and the beginnings of forward motion should help the slop effect.  All I know for sure is it moves sideways pretty fast compared to the boat accelerating.
Cranking the sails in to attempt this (at least in my albeit limited experience) is much more likely to get the boat heeling and water rushing sideways to create another capsize as it is to go over the back. 
Not if you sail away on a broad reach!!   But you still need to achieve steerage-way to get to that broad reach and the sloshing problem happens fast with water on top of the mkIII bouyancy tank.   I'm not saying it won't work...just in my bathing experience it seems questionable.   Cranking in sails to get water draining from the tubes will be a more sure thing than slopping it over the back tank whether on a broad reach or not.
It might work in some situations but a second choice I think to vigourous bailing with the board up and jib backed as you described. 
Backing the jib is for heaving to, which I don't like the thought of with the boat full of water. After a capsize, Marc and I let both sails rag completely, and get the board full up as soon as we get back into the re-righted boat, which in my experience lets the boat stabilize itself sideways to the wind without help from the rudder - a good position from which to begin sailing the water out after a bit of bailing. Regardless of the W type, to sail dry, you want the bow out of the water as much as possible, i.e. both crew on aft tank or near that.   I've had good success with the heave to while bail out approach.... no problems, jib backed and all... if nothing else getting the jib quiet seems to improve ones sense of calm in the recovery from the recent panic.   Maybe there is a down side, but what is it?
However even better might be having a set of stern drainage tubes with which one could sail the water rapidly out of the boat.  I think I've talked myself into another boat project.
I'll look forward to your reports on how this works out!!   There may be a few other projects in the way first... but I think it could work.
Andrew Haill