Could you Make a sailboat completely watertight?

[jeepers]

[QUOTE=
On some vessels (most commonly cats) positive floatation is incorporated into the build, although in many cases the vessel will only be slightly buoyant so although it will not sink it is not necessarily habitable, especially if inverted.[/QUOTE]

Very good comment.

I have done the initial analysis/design/concept for an automatic self righting system for multihulls.

[jalmberg]

Originally Posted by Arthurgifford

If you were to make a sailboat that was 100% watertight and made of say, steel, could that boat theoretically survive any potential storm at sea? Was just curious about this.

Yes, that would be called a sea worthy boat. Anything else is an accident waiting to happen 😵

[Buzzman]

Oddly enough, as the owner of a trimaran, this idea has been a lot on my mind also, and I have been investigating the various issues.

So, assuming you have a boat and wish to make it watertight - as opposed to designing some newfangled 'lifeboat with sails' - there are issues others have raised as well, but let me summarise what I've thought of so far.

Firstly, and perhaps most obviously, is the companionway. The traditional sliding hatch with washboards arrangement fitted to 99% of sailboats is inherently non-watertight. Especially if rolled. more especially if upside down/capsized. A solid potential outcome for a multihull..perhaps less so for a keel-balanced mono...provided the keel remains attached. Cheeky Rafiki, anyone...??

Best way to think of the issues is - imagine the boat is upside down. (With a trimaran like mine, this is easy to imagine, as multihulls are inherently just as stable upside down as they are right way up).

So the deck then becomes the hull, and therefore needs to be watertight.

Hatches, ports, cable glands, stay bolts, etc etc etc. Every penetration in the deck is a potential leak point.

But the companion is the biggie.

A few sailors, like Roger Taylor of Ming Ming fame (he's on YouTube, do your homework) has rid himself of this issue by adding a sloped bulkhead containing a normal glass/perspex/ally hatch for egress/ingress, protected by a small hard+soft dodger arrangement.

Someone with more funds than Roger might ask a hatchmaker (and I mean ship builder, not hatch-making company like Gebo or Lewmar) to make a proper "waterproof hatch", as in the sort of thing ships have as watertight doors in bulkheads, with several 'dogs' to locate it and either a large 'beam' to latch it, or a twirled wheel to dog it down tight, submarine hatch style.

Now the issues for all these is that if you are using the hatch often (as you do) the chance of the hatch seals becoming degraded is almost unavoidable, so a seal which is in a 'trench' such that during normal passage you can't reach the rubber/foam seal is probably a useful idea.

The other issue as people have pointed out is air. Once upside down (or even right way up but watertight) getting air in can be an issue.

One way to achieve this is using modified dorades, with delivery pipes on the inside of the hull that open below the inverted waterline. IOW, if rolled water cannot enter, and while upright, the normal airflow can enter.

If completely rolled 180, this won't supply air, but it might be possible to open say the galley sink seacock, enabling air supply into the interior of the boat. Just be quick to close the seacock if the boat rolls upright again! Just in case!

It probably would help to have only fixed portholes and not opening portholes, but if you do, then they need to be able to be dogged down tight to prevent water ingress. And we all know how well ports are normally sealed. As in: not at all well, so re-doing this so they ARE sealed - properly - is a priority.

The real issue, for me at least, is what to do if the boat turtles or pitchpoles end over while I'm outside in the cockpit, and finish up on the bridgedeck or astride the centre hull, with no way back inside, and potentially the companionway open and the waves sucking out everything even remotely loose inside the boat, as happened to John Glennie and his crew on Rose Noelle.

I'm endeavouring to design something custom to my boat that will be a combination of Roger Taylor's approach, but featuring a larger, longer door, that is spring-loaded, so it automatically shuts all the time, unless latched open, which would only be done at anchor.

This coupled with a removable dogged hatch cover that would attach to the inside of the frame of the companion, so if turtled and inside, I could then make the hatch watertight from inside. I've not finalised this yet but have some ideas mulling about. Getting water out of the baot then becomes an issue, but I have read that the inlet and outlet hoses of a Gusher manual pump can be physically reversed, so water inside the boat can be pumped to the outside. Needs investigating, but promising.

I will also be fitting a small hatch to a compartment in the underside of the wing that will contain basic 1st Aid items for use if capsized at night in a storm (the most likely scenario) such as a line, to lash onto the (built in) lashing points; a bottle of water, some food bars; a space blanket; and a small japanese push-pull wood saw to cut my way in via a pre-designated spot that is marked in the hull coating. (I got this idea from Jim Brown's Multihulls book). So if it's too dangerous to swim down into the cockpit and enter the boat via the companion, I could cut my way in through the hull, as Glennie and Co eventually did.

Obviously, my boat has a deck-stepped mast. I think it might be near impossible to make watertight any boat with a keel-stepped mast, but certainly any electrical cables going to the mast, or to instruments, would need to be made completely watertight, not just so-so watertight as is the usual practice. A simple gland with cable running through it might not be enough. Built in plug disconnects might be necessary. And which are not widely available as far as I know. So, basically a plate with male connectors that bolts on either side of the bulkhead, with a wide shoulder around the main connector that can be sealed with butyl underneath and then through-bolted to ensure no leaks. I'm yet to see what I'm describing, so not sure if it even exists.

So, yes, it's probably possible to make a boat completely watertight, but there is a lot of additional work required and, as with all things 'boat', at additional cost.

As with everything, it's about 'probabilities'. Most boats don't sink via water entering through the companion way. And making something else might not be popular or 'saleable' in the ordinary market, so boatbuilders just stick with the accepted methodologies. Only eccentric weirdos bother doing anything else, and usually have some special and compelling reason to do so.

And like Roger Taylor, or me, or the OP, eventually find a way to fix what they can and live with the rest...

[jalmberg]

I doubt if Ming Ming is air tight, a mono hull doesn’t need to be, since she won’t be inverted for long. But as Roger shows, it’s not rocket science to build a water tight hatch. Mine, for example, are simple aluminum boxes that cover the 4-inch combings around my hatches. A strip of foam around the inside makes them water tight. We’ve had plenty of blue water on the foredeck and never leak a drop. Same thing for the small companionway, except for the single 3/4 inch drop board, which is bulletproof after we dog down the cover. It would leak a bit in the unlikely event of an inversion, but not enough to worry about. The companionway hatch also has a 3/4 inch thick plastic dome so you can keep watch while buttoned up tight — an important consideration.

[Buzzman]

IIRC Roger said specifically he designe dhte entry hatch to prevent the boat being swmaped by following seas, or taking on tons of water if rolled with the 'standard' companion open.
he also designed the raised coachroof with fixed ports so he could see out, and steer the boat, without having to open the hatch and let in cold air in the Arctic areas he sails most.
So different reasons for doing what he did to my reasons, but the execution is similar.
Never suggested his boat was 'air tight', and don't think he would either, but it's mostly 'water tight', which was the subject of the thread.

[Seabeau]

Interestingly enough, boats with no, little or adjustable underwater appendages, when retracted into the hull, are safest from breaking waves.

[Adelie]

Originally Posted by Seabeau

Interestingly enough, boats with no, little or adjustable underwater appendages, when retracted into the hull, are safest from breaking waves.

You mean that boats with centerboards are less likely to capsize?

Where’d you find that research?

[Seabeau]

Originally Posted by Adelie

You mean that boats with centerboards are less likely to capsize?

Where’d you find that research?

As long as the board is up, the centerboard hull has little, if any grip in the deeper water and if pushed upon by the faster moving surface water, the hull will simply slide sideways. Part of the information is contained within Alard? Coles, "Heavy Weather Sailing" section on multihulls and their interaction with breaking surface water because multihulls generally have no deep keels on which to "trip" on the deeper slower water and the remainder, is due to my personal observations, after having sailed a Presto 36 centerboarder for many years and having actually slid sideways upon several occasions after being struck amidships by breaking waves. I knew from stories from Ralph Middleton Munroe, the designer and others who had owned and sailed his vessels, that his boats could do this, but I do not recommend trying it unless you have absolute faith in the design and the physics involved. A 36 ft. sailboat sliding sideways is somewhat disconcerting.

[Buzzman]

I was similarly curious about the comment, but have also heard as scuttlebutt that multihulls slide sideways with boards up when hove to or otherwise hit by beam on waves.
Not yet experienced it myself, but could imagine it would be disconcerting to say the least. Effectively, you are surfing down a wave - sideways..!

[Seabeau]

It was a view of several old films, showing 19th century rowed life saving boats in breaking water, being swept sideways, that first showed me that this sliding effect was indeed possible. When it first happened to me, I was motoring with the board up, across one of the many bars entering St. Catherine's Island Sound, GA., when an errant wave struck me between amidships and the stern quarter. On a Presto 36, it's designer Ralph Middleton Munroe, to increase hull buoyancy, had the hull flare continue up to the top of the gunwales which are a full 10" high. The surface wave drove the boat over unto the top of the gunwale and then the hull broke loose and slid sideways about 30 feet. As I mentioned previously, I was most disconcerted, but also elated at the same time. The story of both the Presto boats and their talented designer can be read in "The Good Little Ship" and "The Commodore's Story", by Vincent Gilpin.

[double u]

Originally Posted by Buzzman

I was similarly curious about the comment, but have also heard as scuttlebutt that multihulls slide sideways with boards up when hove to or otherwise hit by beam on waves.
Not yet experienced it myself, but could imagine it would be disconcerting to say the least. Effectively, you are surfing down a wave - sideways..!

...& then you dig in the gunwhale...
(imho another BS theory of the type "MY boat is best!")

[Seabeau]

Originally Posted by double u

...& then you dig in the gunwhale...
(imho another BS theory of the type "MY boat is best!")

"Theory" or physics?

[goboatingnow]

Originally Posted by Seabeau

As long as the board is up, the centerboard hull has little, if any grip in the deeper water and if pushed upon by the faster moving surface water, the hull will simply slide sideways. Part of the information is contained within Alard? Coles, "Heavy Weather Sailing" section on multihulls and their interaction with breaking surface water because multihulls generally have no deep keels on which to "trip" on the deeper slower water and the remainder, is due to my personal observations, after having sailed a Presto 36 centerboarder for many years and having actually slid sideways upon several occasions after being struck amidships by breaking waves. I knew from stories from Ralph Middleton Munroe, the designer and others who had owned and sailed his vessels, that his boats could do this, but I do not recommend trying it unless you have absolute faith in the design and the physics involved. A 36 ft. sailboat sliding sideways is somewhat disconcerting.

This has all been essentially “ theory. “ there simply isn’t enough reliable data to back up any of these “ slide down a wave “ theories.

In my limited experience of being in breaking waves is that there are so many variables in play that anything can cause disaster. Boats can trip over their own freeboard ,on gunwales etc.

[double u]

here a nice comparison of the stability of a centerboarder with a keelboat (& by an advocat of centerboarders...!)
https://voilesetvoiliers.ouest-franc...e-33e04757e9a2

& don't just look at the angle, look at the areas under the curves...

[valhalla360]

Originally Posted by Arthurgifford

If you were to make a sailboat that was 100% watertight and made of say, steel, could that boat theoretically survive any potential storm at sea? Was just curious about this.

Strictly speaking: the answer is NO.

Example: Boat falls off a 50ft breaking wave onto a rocky outcropping, it most likely splits apart. Even with no rocks, dropping off a breaking wave and hitting the trough at 20-30mph could be enough to break the hull.

Of course a stoutly built steel boat that is well sealed will stand up to a lot but as with the Titanic, nothing is unsinkable.

In the practical world: As others have said, the passengers are likely to give out long before the boat does...and this applies to the vast majority of cruising boats.

CG 47ft Motor Lifeboat is pretty close to what you describe. I recall seeing on go out the channel at Holland, Michigan in a storm (I was ashore). There were 30fters and it just dropped like a rock when if fell off the wave crest. I'm shocked it didn't hit bottom. They quickly turned around and high tailed it back in the channel because it was crazy to go out in those conditions.