03 March 2016

Keeping The Water Out

The best safeguards against calamity are foresight, the intelligent anticipation of trouble and the imagination to see where a particular decision may lead. -- D.A. Rayner "Safety in Small Craft"

Now that my book, An Unlikely Voyage, is finally launched, its a bit of relief to have some time to get back to blogging. Last time, I made a top-level list of ways to minimize the risk of taking the Blue Moon across the Atlantic, twice, to participate in the Jester Challenge.

This time, I will drill down into the most critical risk: minimizing the risk of sinking.

Minimizing the risk of sinking is, of course, the one necessary thing to do. King Neptune can exploit every weakness in your boat and test every skill in your seamanship toolkit, but as long as your boat is still floating, you won't drown.

Photo from rescue ship HMS Clyde off the Falklands

1. Minimize the risk from holes drilled below the waterline.

What's the point of building a seaworthy boat if you are going to drill a bunch of holes in her bottom? As soon as you do, you have to start worrying that your through-hulls are of the highest quality, that they close when you need them to close, and that all the pipes and hoses connected to them are equally sound. And if you have an inboard engine, you have to drill a bunch more holes for the prop shaft, coolant water, etc.

Eric Forsyth nearly had Fiona sink under him off Cape Horn shortly after we left them in Brazil a couple years ago. The reason? A hose blew off a through-hull in a storm and the boat nearly foundered before Eric could find and stop the leak.

The Blue Moon has no through-hulls, and no engine so no stuffing box, etc. However, momist -- one of my readers -- cleverly pointed out that she does indeed have holes drilled for her keel bolts.

One of my hobbies is taking pictures of the Blue Moon's bilge in mid-winter. I take great pleasure in seeing how dry it is. I really need to get a vacuum in there!

Anyway, you can see the nuts on some of the keel bolts. I haven't run out to count them yet, but I believe there are 5 or 6 heavy bronze bolts. It's hard for me to imagine the keel falling off, but if it did, presumably water would come in through the holes drilled for these bolts, at least until the boat flipped over from the weight of the mast.


Keel bolts in the Blue Moon's (dry!) bilge
Michael, another reader, mentioned the bolts holding on the rudder gudgeons. At least one of these is below the waterline. I don't know if the bolts go all the way through the hull, though. Must check.

2. Minimize the risk from the hull-deck joint and other joints/holes above the waterline.

Apparently some boats leak so badly at the hull-deck joint that they can take on serious amounts of water when forced to sail with the rail in the water in bad conditions. I think this is mainly a problem with fiberglass boats, but it's something I need to look into a bit more with the Blue Moon.

My keel-stepped mast does go straight through the deck. The mast partner (the reinforcement around the deck hole) looks very strong, but I will need to double-check that.

Before pulling the boat for the winter, I was making do with a mast boot made from duct tape. Not pretty but effective. I will want to upgrade this to something really strong and watertight when I re-step the mast.

The Blue Moon has the best kind of chainplates: those that are through-bolted with substantial backing plates to the side of the boat, rather than the usual type which penetrate the deck, which is an all too common cause of leaks.  My chainplates have probably never been re-bedded since the BM was launched, so I will do that, just to make sure they don't leak.

Cockpit lockers can turn into huge holes in the boat when boarding seas find a way to wrench them open. Roger Taylor hates cockpit lockers so much that he sealed them all up in his little Mingming. In the past, I've occasionally wished for cockpit lockers, but since I don't have any, there are none to seal.

Deck hatches also need to be strong enough to resist the prying fingers of King Neptune. The Blue Moon has a single, rather small deck hatch on the foredeck. It's stoutly built, but the latch is flimsy. Definitely need to replace the current latch with something I can trust in any kind of weather.

Another reader, jerry, made me think about the through-hulls for my cockpit drains. There are two of them, both above the waterline, so I initially discounted them as risks, but then I realized that they are only above the waterline when the boat is sailing straight up. As soon as she heels over, one of them is underwater.

3. Minimize the risk from holes in the cabin

The strongest boats have flush decks and no cabin at all. The Blue Moon does have a cabin, but it's small, low, and strongly built.  The main risk is that the cabin can be ripped off the deck entirely by bad weather. It's hard to imagine how I could make the cabin stronger stronger than it already is, but I will at least think about it.

I guess the ideal boat would have no hole in the deck at all, but one is usually required to go below decks. In most boats, this hole is called the companionway. Its a significant risk because it's usually the biggest hole in the boat.

The Blue Moon's companionway is about as safe as you can make it: it's quite small and is safeguarded by a high bridge deck, well above the level of the rails. Even if the cockpit was full of water, not a drop would enter the companionway.

Companionway drop-boards can quickly become liabilities when a boat is knocked down. My new drop-boards are solid hardwood and fairly small, so I don't think they could be bashed in, but they could easily fall out if the boat was inverted, letting in huge amounts of water. It would also be hard to replace them at sea if they suddenly went missing, so if I keep my companionway (see below) I will want to:
  • attach the drop-boards to the boat with lanyards, so they can never go overboard
  • provide some sort of locking mechanism, so I can latch the boards and companionway hatch from the inside
It's already possible to lock the companionway and drop-boards from the outside to secure the boat while in the cockpit, but rather than using a padlock as usual, I'd prefer something just as secure but easier to open, such as a locking carabiner attached to the boat with a lanyard, so it's always ready for use. 

Developing good habits, such as closing the companionway when its not in use, are equally important. Its no good having locking drop boards if they are not in place when the rogue wave comes aboard.

Roger Taylor has eliminated the companionway, drop-boards, etc., on Mingming, replacing them with a very strong aluminum hatch, like on a submarine. Other Jester boats have taken the same approach, signaling that companionways are a significant risk. Eliminating the companionway means making major alterations to the cabin, so it's something I will have to think about.

The Blue Moon's cabin has eight -- count them... eight! -- opening portlights. Great for letting in summer breezes; bad for keeping out water. However, they are all small and high quality bronze ports, so I'm not too worried about them.  I will re-bed them as I paint the cabin this spring, to make sure they are watertight. I will also look into replacing the gaskets that compress and seal the opening when the covers are dogged down. I might also look into building plywood crash covers for them, in case of really bad weather.

Obviously, remembering to install the covers before the storm hits will be important.

4. Minimize the risk of new holes forming in the boat

Besides the holes that are already there, I must consider the possibility of new holes forming.

New holes can be created in the hull when the boat is subjected to unusual wrenching forces, such as those exerted on the hull by the rig in a storm. There are many stories of wooden boats opening up their seams as the rig places twisting forces on the hull. The Blue Moon is strip-planked, meaning that each of her planks is nailed and epoxied to the next one, creating an inch-and-a-half thick monocoque (French for "single shell") structure which should be less likely to open up than a traditionally planked boat. The main risk is glue failure in one of the joints. I'm not sure if it is possible to predict this sort of failure in advance, but it might be worth while having the boat surveyed by an experienced strip-plank builder, just to make sure.

The Blue Moon is heavily framed, which help her resist King Neptune's attempts to bash her ribs in. She also has a raised deck, and heavy deck beams. One thing she doesn't have is bulkheads. This gives her a great open feeling down below, but a forward bulkhead, near the mast, would undoubtably make her stronger and more able to resist wrenching forces. The is the one major structural change to the boat that I'm seriously considering.

Her low gaff rig also helps minimize the twisting force exerted on the boat by the rig. Reefing early and often will also help.

Several readers mentioned the risk of an anchor breaking lose, and banging holes in the deck or hull; likewise the risk of the mast going overboard and doing similar damage while it's alongside. I think we can lump all these risks into one sub-category: the risk of things breaking loose and banging new holes in the boat.

Most obviously, new holes can be created when the boat runs into a heavy, solid object, such as the proverbial log or submerged container. But this is a big subject and I'm already running long, so I will leave this topic for next time!

Meanwhile, if you can think of additional horrifying ways for water to get into a boat, please leave them in the comments section below. Forewarned is forearmed.

Next Up: Minimizing the Risk of Getting Run Down


  1. Well . . . you did ask. What holds the keel on? In fact, what kind of keel is it? Forgive me if this has already been expounded upon in your blog, my memory is not what it used to be. There are countless horror stories of apparently sound boats losing their keel because the keel bolts have waisted with corrosion within the holes they pass through. The best test is withdrawing one or two, but they can be x-rayed.

  2. What if your cockpit runs full of water? Aren't there drainpipes from the cockpit through the hull?

    1. Good point. Yes, I do have two big cockpit drains with through-hulls, but they are above the waterline. Because of that, I tend to forget about them, but you are right... in mid-ocean in bad weather, they could be a big problem if they failed, even if they are above the waterline. Thanks for making me think about this. It's amazing how easy it is to overlook stuff like this.

  3. Snap! The two obvious ones, keel bolts and cockpit drains, have been mentioned. But what about rudder tubes (not in your case) but have a think about the through bolts attaching your rudder to the transom, and the efficacy and wear of the pintles and gudgeons and bottom bearing. And apropos the fore hatch, more important than the latch is how well it is securely hinged - it's the front end that usually takes the uplift load when a boat buries its bow. Are the hinges good, and what and how are they screwed to? Also, spars falling over the side make good battering rams, and if you are attaching lanyards to things, think about the slack in the lanyards, and their leads - if it's a cats cradle to sort out, you may not put in the pieces until too late, and may not be able to clear the tangle in extremis - and there's a tripping hazard. One rule I learnt was never put anything on your boat unless it can do/achieves three things. Think about it.

    1. I have this urge to run down to the boat and see exactly where the gudgeons are fastened. I can't find a photo that shows them. The Blue Moon has an aft-hung rudder on a full keel, so one is at the bottom of the keel post, and one is above the waterline on the transom, but I'm not sure where the middle one is. Will have to look. Since writing this post the other day I've been thinking about the hinges, which are on the wrong side. The hatch opens towards the front now. I assume they are through-bolted, but will definitely check. Spars: good point. I have heavy-duty wire cutters on my list in case I have to cut the shrouds away, but actually my short, solid wood mast with two forestays, four shrouds, and two running backstays is probably the toughest thing on the boat. If it goes overboard, I'm in the storm of the century.

  4. How do you secure your anchor? Or better your anchor and the spare one? In a heavy sea they could possibly wreck the deck or else.

  5. Another good idea. I think the best thing to do is to stow the anchor down below while at sea. That eliminates the risk of it breaking lose, and gets the weight off the bow moves it down low where it belongs.


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