Hull designs .... questions

[Ungvar]

Originally Posted by Dockhead

The only really good solution I've seen is Dashew's -- his sailing boats are separated into three watertight compartments, and there are no hole at all in the bottom in the main, central compartment.

This, in my opinion, is an excellent solution to the op's problem.

A seachest located in a small engine compartment with high dewatering capability is a great way to improve survivability and is fairly easy to accomplish with steel and aluminum yachts, although some expensive glass yachts have this feature.

For this to work, you need to be diligent about keeping watertight hatches sealed both at sea and at dock, unless entertaining or performing maintenance.


You also need to be diligent about using water tight through bulkhead fittings and not using too many of them.

People sink when a watertight compartment, like the forepeak, fills with water and then have a bulkhead fitting fail, filling the boat up with water.


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[K_V_B]

Originally Posted by Dockhead

One way to reduce the holes is to use a sea chest, but I'm not entirely sure that replacing several small holes with one giant hole is really progress.

Or you can (especially on metal boats) use standpipes, that extend above the waterline.

[PelagicSam]

Wow. Thank you to everyone for your comments. Looks like i have a lot to look into . Thanks for all of the links provided. I will have to put this on my back burner of my mind to process it all. Great forum nice to see so many responses.

[tuffr2]

All boats are sinking. It is just a matter of degree. Man's attempt to keep water where they want it is a never ending losing battle.

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[Dockhead]

Originally Posted by K_V_B

Or you can (especially on metal boats) use standpipes, that extend above the waterline.

Yes, good point, I had forgotten about those.

They need to be really, really sturdy, though. If you break one off, you're in trouble. Also there is a siphon risk, and that is a puzzle for things like cooling water.

[a64pilot]

Instead of stand pipes, I believe you may be thinking of a sea chest?

[barnakiel]

IMHO just keep on reading what you may google up and keep an open if critical mind.

Look up Zaal, Koopmans, VDS, Kasten Marine and similar websites. They all give you valuable pieces of info. Look up K&M they build fine small boats in metals.

Look at real life examples of boats you do like. Look at alternatives. Imagine the kind of use you want from a boat.

Do not get fixated on minimum holes. This is not very relevant and most boats have a handful. Our small one has ... errrr 7?

Places you may want to visit will be France and Holland mostly, I think. One offs are build elsewhere too.

b.

[barnakiel]

Yep. I nice sea chest with entry well above the line is a good solution.

Center-boarders and drop-keelers can use the board's chest as one.

b.

[Dockhead]

Originally Posted by a64pilot

Instead of stand pipes, I believe you may be thinking of a sea chest?

They're not exactly the same -- a sea chest is like a standpipe but with multiple connections. Like a manifold. And usually much larger in diameter. Which makes me a bit nervous.

Many metal boats have standpipes -- so a hole for each purpose, but led to above the waterline.

[carlheintz]

My 2 cents:
(1) through-hulls are no more dangerous than anything else ASSUMING you maintain them. Most failures aren't on the through-hull itself, it's on the attachment to the tubing on the inside. That's why the standards call for double clamps. The weakness is at the point where the hose attaches to the through-hull. Most people spend far too little time checking these. My protocol is to check them every time I leave the dock. Try the lever, make sure it closes, check the clamps, check the hose for cracks, be sure there is an emergency plug tethered to something very close by so I could grab it in an emergency in the dark and stop the leak.

(2) Steel vs Aluminum vs Plastic (fiberglass)... this isn't even a decision. Fiberglass is strong, easily repairable, relatively light, and it doesn't corrode. Forget about "All is Lost." It's the most stupid movie I have ever seen. The guy was an idiot, on multiple levels. If you want a strong boat, capable of crossing oceans with ease, go for a good blue water fiberglass boat. A Cal 40 or Tartan 37 are wonderful boats. There are many others... Niagara 35 comes to mind... which won't cost you much, you can easily handle with one and a half people, and will get you there safely.

(3) as one who has crossed oceans, um, let's just say that coastal sailing is a lot more fun. More to see, more to do, you can always take a break and go ashore for a night at a fine restaurant and maybe even a nice hotel. Spending two weeks out in the middle of nowhere is not at all romantic. Plus, if, and it's a very small if, you have a problem, you are in a world of hurt. If you get into a shipping lane, you had better be very alert, because the big boys barrel along on autopilot and have tight schedules to keep, which means you are in serious peril. They won't see you, either before or after they blow right over you. Oh, and even if you are a half a mile away (which is way, way too close), the wake will whack you around a bit. The most fun, however, are the squalls, storms, whatever. Near shore, you just get to a protected port and pop a brew. Out there, you deal with it, which can range from getting pummeled with freezing rain to worrying about lightning and being broached. (as one who has had his entire cabin top under 2 feet of water, let me assure you, it is NO fun). Sailing in 30 foot rollers is challenging, to put it mildly. No thank you.

[Dockhead]

Originally Posted by carlheintz

My 2 cents:
(1) through-hulls are no more dangerous than anything else ASSUMING you maintain them. Most failures aren't on the through-hull itself, it's on the attachment to the tubing on the inside. That's why the standards call for double clamps. The weakness is at the point where the hose attaches to the through-hull. Most people spend far too little time checking these. My protocol is to check them every time I leave the dock. Try the lever, make sure it closes, check the clamps, check the hose for cracks, be sure there is an emergency plug tethered to something very close by so I could grab it in an emergency in the dark and stop the leak.

(2) Steel vs Aluminum vs Plastic (fiberglass)... this isn't even a decision. Fiberglass is strong, easily repairable, relatively light, and it doesn't corrode. Forget about "All is Lost." It's the most stupid movie I have ever seen. The guy was an idiot, on multiple levels. If you want a strong boat, capable of crossing oceans with ease, go for a good blue water fiberglass boat. A Cal 40 or Tartan 37 are wonderful boats. There are many others... Niagara 35 comes to mind... which won't cost you much, you can easily handle with one and a half people, and will get you there safely.

(3) as one who has crossed oceans, um, let's just say that coastal sailing is a lot more fun. More to see, more to do, you can always take a break and go ashore for a night at a fine restaurant and maybe even a nice hotel. Spending two weeks out in the middle of nowhere is not at all romantic. Plus, if, and it's a very small if, you have a problem, you are in a world of hurt. If you get into a shipping lane, you had better be very alert, because the big boys barrel along on autopilot and have tight schedules to keep, which means you are in serious peril. They won't see you, either before or after they blow right over you. Oh, and even if you are a half a mile away (which is way, way too close), the wake will whack you around a bit. The most fun, however, are the squalls, storms, whatever. Near shore, you just get to a protected port and pop a brew. Out there, you deal with it, which can range from getting pummeled with freezing rain to worrying about lightning and being broached. (as one who has had his entire cabin top under 2 feet of water, let me assure you, it is NO fun). Sailing in 30 foot rollers is challenging, to put it mildly. No thank you.

Through hulls are pretty safe. But they do fail, and they often fail in ways which you could not prevent with all the inspections in the world. Hoses just split sometimes. Less likely when they are relatively new, but it happens. Even good bronze through hulls can dezincify in a non-obvious way, and just fall apart. Doesn't happen often, but enough to be the #1 cause of sinking (see above).



Concerning metal vs plastic -- this is a pretty flip dismissal, and I think the subject is worthy of a less superficial look than this.

Plastic is a marvelous material with many advantages, and is probably the best choice for a big majority of sailors. But plastic also has drawbacks and it's not perfect for everyone. Metal also has a few really big advantages. My next boat will be alu.

[carlheintz]

I think you bring up some very good points. I agree. I totally skipped making a scientific and objective analysis of plastic vs steel vs aluminum. But then, it was only my 2 cents, and we all know what that is worth!

[PelagicSam]

Reason that i decided to look towards a steel or aluminum hull was the possibility of coming into contact with floating debris or whale etc etc . But i was thinking about the thru hulls and there are just so many ways a boat can sink.
Someone mentioned over the gunwale waves as the #1 reason for sinking while not at the dock. I am really a newbie on this one, and have to ask why . Is the cabin door water tight when shut? Cockpits take too long to drain ?

[Don C L]

Originally Posted by PelagicSam

Reason that i decided to look towards a steel or aluminum hull was the possibility of coming into contact with floating debris or whale etc etc . But i was thinking about the thru hulls and there are just so many ways a boat can sink.
Someone mentioned over the gunwale waves as the #1 reason for sinking while not at the dock. I am really a newbie on this one, and have to ask why . Is the cabin door water tight when shut? Cockpits take too long to drain ?

Not so much the cockpits don't drain, but many when full drain right into the cabin since the entry is so low. A large cockpit is nice for entertaining, but not so nice if you get pooped. Most folks don't NORMALLY close up main hatch in good weather and if you are knocked down (rare) the ocean may pour in (over the gunwale) and become a "free surface" that can hold you on your side for a while and let even more water in. But in bad weather most folks DO close the hatch. You may be nursing too much fear of sinking. Get a good liferaft, survival suit and epirb and that should asuage your fears. And keep up with the normal maintenance of through-hulls and stuffing box, of course. I am pretty happy with plastic, but if I were planning to go polar I'd prefer a metal hull. IN my own plastic boat, with its molded in long keel I am pretty sure I'll be ok with hitting a whale. (I am more worried about the whale.) A lost container, well I may get a hole, but I have stuff to stuff into random holes right now so I live in the bliss of a false sense of security.

[Smokeys Kitchen]

Hi Pelagic,

Looks like you have gotten a lot of good information here. I would like to add one more source - Michael Kasten. He is a boat designer, and while you may not be partial to his designs, he does have a list of good articles about yacht design, including types and materials. Most are written in fairly easy to understand language. Here is a link to his design site:

Articles on Yacht Design and Boat Building.

I found them a great place to get some basic info on building material. He also has a few paragraphs on the minimum size for steel boat issue.