Cruisers & Sailing Forums (https://www.cruisersforum.com/forums/)
-   Monohull Sailboats (https://www.cruisersforum.com/forums/f47/)
-   -   crash bulkheads on production boats? (https://www.cruisersforum.com/forums/f47/crash-bulkheads-on-production-boats-227151.html)

unbusted67 29-11-2019 18:41

crash bulkheads on production boats?
 
Are there any production boats that have separate bulkheads for rudder spaces? What about a collision bulkhead in the bow? Seems like a no brained from a safety standpoint.

billknny 29-11-2019 18:49

Re: crash bulkheads on production boats?
 
My Amel 53 has SIX water tight compartments.

The chain locker The forward cabin. The main cabin. The engine room. The aft cabin. The aft locker. Each can be fully isolated in the event of a hull breech keeping the boat afloat.

Like you said, it’s a no brainer. With a LITTLE design work it doesn’t even add much cost.to the build.

But nobody else does it. The dollar rules.

atoll 29-11-2019 19:01

Re: crash bulkheads on production boats?
 
all the prouts had them in the bows and sterns compartments
pretty common on most production catamarans

billknny 29-11-2019 19:09

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by atoll (Post 3026140)
all the prouts had them in the bows and sterns compartments
pretty common on most production catamarans

True enough. But Amels are still the only production boat I know of that divides the accommodation spaces into water tight compartments.

S/V Illusion 29-11-2019 19:10

Re: crash bulkheads on production boats?
 
Given many people routinely want easy access to these spaces (forward cabin, main cabin, engine, etc...), they are routinely left open. If you’ve ever tried closing a door against the flow of anything large enough to sink a boat, it seems like a “feel good” but futile option.

It isn’t as much a matter of cost as it is practicality.

funjohnson 29-11-2019 19:23

Re: crash bulkheads on production boats?
 
There are quite a few productions boats with watertight bulkheads forward- even Catalina and Hunter have these advertised now- but they are typically so tight to the bow to maximise interior space that the value they add is small.

One thing we did in the last boat was to make the area under the v-berth bed watertight. It took a little glass work to seal off the bilge, tab in the bed base all around to the hull, and then bolt the lids in place with rudder gaskets, but this gave us an additional 6' of protection from the bow back and to a foot over the waterline. The area was already dominated by a polyurethane water tank, so i didn't lose any storage. I don't think I've ever seen a production boat make the v-berth bed into a double bottom.

Matt

Dockhead 29-11-2019 19:40

Re: crash bulkheads on production boats?
 
Moodys have crash bulkheads forward, between the anchor locker and the main hull volume. On my boat this is a substantial space forward, and the hull is skinned in Kevlar besides that for crash protection.


Dashew's boats including the Sundeer have watertight bulkheads forward and aft. Very interestingly -- these boats don't have hull penetrations in the main hull volume -- very nice!

funjohnson 29-11-2019 19:51

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by Dockhead (Post 3026162)
Moodys have crash bulkheads forward, between the anchor locker and the main hull volume. On my boat this is a substantial space forward, and the hull is skinned in Kevlar besides that for crash protection.


Dashew's boats including the Sundeer have watertight bulkheads forward and aft. Very interestingly -- these boats don't have hull penetrations in the main hull volume -- very nice!


Every Hunter over 33' has Kevlar forward too :biggrin: They don't define how far back the Kevlar goes, but even if it's an inch, they can add it to the advertisement.

If I remember correctly, the Moody has it back to the keel stub.. is that right? Is it on the inner or outer side of the coring?

Matt

robwilk37 29-11-2019 21:00

Re: crash bulkheads on production boats?
 
my project has a collision bulkhead between the forepeak and the chain locker, isolated rudder post, and is effectively double-hulled with locking lids on all lockers from 8"above the waterline on down. not hard to incorporate when you gut the boat and start from a bare hull...

thinwater 29-11-2019 21:11

Re: crash bulkheads on production boats?
 
My PDQ had 2 forward and 2 fat in each hull. They didn't restrict access.



a. They had forward and aft sections had 6" ports, which is all they needed.



b. The next set were bulkheaded either to the deck or nearly so, with full access through big hatches.


Finally, they were positioned such that ALL of the through hulls were bulkheaded. In fact, on my delivery trip I had a through hull failure. No big deal. Two days latter, at the dock, I pumped out and fixed the problem. Really, they paid for themselves that day just in the water damamge that would have been caused by a foot or so of flooding.


Seems obvious to me.

Tillsbury 29-11-2019 21:11

Re: crash bulkheads on production boats?
 
I’m sure a fair number of larger boats have them to some extent. Behind my anchor locker is a sizeable sail locker accessed only from a deck hatch, and the rear bulkhead there is a good 8-9 feet from the bow with no opening into the main boat interior. It’s well tabbed to the hull as it is the support for the optional cutter rig. Only any use for a direct frontal hit of course, but it’s a start. The rear lazarette is huge and only accessible from two relatively small hatches in the rear cabins. It has occurred to me that it would take a relatively small amount of glasswork and reinforcing of these hatches to isolate the entire rear 6-8 feet of the boat too, which of course includes the rudder post - a potentially catastrophic failure possibility. I don’t know if I could make it 100% waterproof but the job is to make it good enough that if it were full to the waterline there would be only enough coming into the boat that bilge pumps could comfortably handle.

s/v Jedi 29-11-2019 21:32

Re: crash bulkheads on production boats?
 
Yes we have watertight bulkheads forward and aft. The living space in between these two is just 38’ in a 64’ waterline boat. This means that both fwd and aft compartments can flood without sinking.

There is a standpipe for discharge in the center section.

robwilk37 29-11-2019 21:36

Re: crash bulkheads on production boats?
 
thread hijack - your standpipe is for galley sink? no seacock? asking because im surprised more boats dont incorporate them...

billknny 29-11-2019 21:46

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by S/V Illusion (Post 3026149)
Given many people routinely want easy access to these spaces (forward cabin, main cabin, engine, etc...), they are routinely left open. If you’ve ever tried closing a door against the flow of anything large enough to sink a boat, it seems like a “feel good” but futile option.

It isn’t as much a matter of cost as it is practicality.

Ahhhh... that's an interesting way of talking yourself out oa a good idea.

On an Amel, the watertight doors open AWAY from the main cabin, so the most likely flow of water is pushing to door CLOSED, and the engine room is sealed always from the main cabin, the only access is down through the cockpit sole. The chainlocker and aft locker have no routine access from the main cabin at all.

It IS a practical solution. I have seen an Amel floating after a hurricane pushed a piling though the hull until it hit the keel. Waterproof compartments WORK.

s/v Jedi 29-11-2019 21:50

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by robwilk37 (Post 3026208)
thread hijack - your standpipe is for galley sink? no seacock? asking because im surprised more boats dont incorporate them...

It is for the pilothouse drains (like cockpit drains), the grey water holding tank has a pump discharging in it, as well as the center compartment bilge pump.

All the sinks and both shower have a gravity drain into the holding tank, just like a house :thumb:

Dockhead 30-11-2019 03:09

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by funjohnson (Post 3026166)
Every Hunter over 33' has Kevlar forward too :biggrin: They don't define how far back the Kevlar goes, but even if it's an inch, they can add it to the advertisement.

If I remember correctly, the Moody has it back to the keel stub.. is that right? Is it on the inner or outer side of the coring?

Matt


Correct. The Kevlar is the outermost layer of the layup (naturally), and goes to the keel stub, so covering all the forward sections. This greatly increases the impact resistance of the forward sections. Kevlar is very weak in compression so it has a weird effect on the structure, increasing stiffness in tension but not compression.



Concerning watertight compartments: I think people are underestimating how difficult it is to build a boat with them. It requires a lot more than watertight doors. The bilges have to separated, it requires separate bilge pump pickups (better, entirely separate bilge pump systems) for each compartment, and it is the very devil to seal the various cables and pipes passing through all these bulkheads. I admire the Amel very much, and I would prefer that approach to what I have, but I like the Sundeer approach even much better. With no penetrations in the main hull volume, the boat becomes practically unsinkable with substantial watertight compartments fore and aft of the main hull volume. The after part of the boat is a large volume including not only lazarette but large volume engine room and technical space. It would suck of course to have this space flooded, but the boat would not sink, and you could work on dewatering it from a safe place. This is really good design.



I hate the fact that the lazarette of my boat communicates with the main hull volume. There is already a substantial structural bulkhead between the laz and aft cabin and the bilge is very shallow there. There are few pipes and cables. It would have been pretty simple to make that bulkhead watertight, requiring one bilge pump and sealing up a pretty small space. The volume of that space is quite substantial.

funjohnson 30-11-2019 05:28

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by Dockhead (Post 3026271)
Correct. The Kevlar is the outermost layer of the layup (naturally), and goes to the keel stub, so covering all the forward sections. This greatly increases the impact resistance of the forward sections. Kevlar is very weak in compression so it has a weird effect on the structure, increasing stiffness in tension but not compression.

.

In an impact, the outer layer is in compression and the inner is in tension. That's why I've always been confused as to where this laminate layer goes in a build. Seeing Lyman-Morse build Kiwi Spirit, the outer hull was carbon/core/carbon/kevlar/carbon which seems to reinforce the idea that the inner laminate is in tension and where the kevlar works best. But a lot of other builders are outer of glass/kevlar/glass/core/glass.

I'm just slightly confused and no amount of Googling seems to clear this up.

Matt

s/v Jedi 30-11-2019 06:28

Re: crash bulkheads on production boats?
 
We have Kevlar on the outer layer of the laminate in the turn of the bilge. This is not so much for collisions as it is for grinding on a reef, i.e. for abrasion resistance :thumb:

Dockhead 30-11-2019 06:51

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by funjohnson (Post 3026296)
In an impact, the outer layer is in compression and the inner is in tension. That's why I've always been confused as to where this laminate layer goes in a build. Seeing Lyman-Morse build Kiwi Spirit, the outer hull was carbon/core/carbon/kevlar/carbon which seems to reinforce the idea that the inner laminate is in tension and where the kevlar works best. But a lot of other builders are outer of glass/kevlar/glass/core/glass.

I'm just slightly confused and no amount of Googling seems to clear this up.

Matt


If you wanted the Kevlar for its structural properties, then perhaps it would make sense to put it in an inside layer. But remember resisting an impact may also involve preventing PENETRATION and a hull breach, and that is what the Kevlar is for, at least on my boat.

noelex 77 30-11-2019 08:46

Re: crash bulkheads on production boats?
 
1 Attachment(s)
Our boat has 5 watertight areas separated with either watertight doors or bulkheads.

It is an expensive way to build a boat, proper watertight doors are not cheap.

This would be overkill for most production boats, but I think they could do a better job in some common areas of water intrusion, such as around the rudder area. As this is close to the waterline a simple coffer dam could provide very effective protection. Some boats have this, but not many.

This is our watertight bulkhead and door separating the owners’ cabin from the rest of the interior, taken during construction:

Bleemus 30-11-2019 09:20

Re: crash bulkheads on production boats?
 
Catalina's newer models have crash bulkheads and foam for impact in the bow below waterline.

funjohnson 30-11-2019 09:20

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by noelex 77 (Post 3026398)
Our boat has 5 watertight areas separated with either watertight doors or bulkheads.

It is an expensive way to build a boat, proper watertight doors are not cheap.

This would be overkill for most production boats, but I think they could do a better job in some common areas of water intrusion, such as around the rudder area. As this is close to the waterline a simple coffer dam could provide very effective protection. Some boats have this, but not many.

This is our watertight bulkhead and door separating the owners’ cabin from the rest of the interior, taken during construction:


And the galley standpipes! I love the dogs for the door top and bottom.... all very proper.

Matt

Lake-Effect 30-11-2019 09:28

Re: crash bulkheads on production boats?
 
Our boat has a watertight, isolated lazzarette :wink:. Sort of like an airbag on a tricycle.

Valmika 30-11-2019 10:29

Re: crash bulkheads on production boats?
 
I don't think I've ever seen a production boat make the v-berth bed into a double bottom.

Matt[/QUOTE]


My old Beneteau 38 under the V berth was the forward integral water tank and I have to think if I hit something in the first 7 feet of the boat at water line I would loose most of my fresh water (I have two tanks) but not take on any salt water

jmh2002 30-11-2019 10:45

Re: crash bulkheads on production boats?
 
I might follow a wider field of sailing news than the average cruiser here, and whilst there have been some noted and publicised events of cruising boats hitting objects at sea that caused sufficient damage to be of major concern, including the boat sinking, I would like to highlight some other events.

In pretty much every single major offshore racing event for the last few years competitors have hit objects at sea and caused serious damage.

This year, I think (I didn't make a spreadsheet, sorry) every single offshore event that I followed the news for had serious collisions resulting in at least one boat (from a relatively small entry list) retiring or returning to port for repairs.

Whilst I appreciate that a lot of these were high speed yachts possibly resulting in higher collision damage, the real point that I wanted to make was from a statistical point of view.

It seems that there is SO MUCH stuff floating around out there now that the odds of hitting something at some stage seem to be quite high these days.

So it seems that positive buoyancy (however you want to achieve that) would be a sensible item to have on the wish list for a future offshore cruising boat purchase.

Because unfortunately the issue of floating debris at sea will only get worse for the foreseeable future.

:boat:

Hardhead 30-11-2019 10:59

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by jmh2002 (Post 3026466)

Because unfortunately the issue of floating debris at sea will only get worse for the foreseeable future.

:boat:

That's a good point. More commerce equals more cast-offs.

AIS and radar may be getting better, but half-submerged objects may be getting worse.

Discovery 15797 30-11-2019 11:12

Re: crash bulkheads on production boats?
 
https://www.sailmagazine.com/cruisin...ision-offshore

jmh2002 30-11-2019 11:25

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by Discovery 15797 (Post 3026489)

Quote:

The real odds of hitting anything while on passage are, however, vanishingly small.

Recent surveys by the World Shipping Council meanwhile suggest that somewhere between 300-700 containers are also lost overboard worldwide each year, excluding unusual catastrophic events. These numbers may seem large, but you must also consider the incredibly vast area over which these potential threats are deployed.
Despite the warm fuzzies that author Charles J. Doane wishes to bestow on us (which mostly seems to be along the lines of 'ah, don't worry about it...') the anecdotal evidence seems to suggest (to me at least) that the odds are changing, quite rapidly...

One can even see it, by the much larger amount of 'stuff' - be that rubbish, junk, debris, etc, that now floats by us much more regularly at sea

:boat:

funjohnson 30-11-2019 11:44

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by jmh2002 (Post 3026497)
Despite the warm fuzzies that author Charles J. Doane wishes to bestow on us (which mostly seems to be along the lines of 'ah, don't worry about it...') the anecdotal evidence seems to suggest (to me at least) that the odds are changing, quite rapidly...

One can even see it, by the much larger amount of 'stuff' - be that rubbish, junk, debris, etc, that now floats by us much more regularly at sea

:boat:

But of those 300-700, how many remain on the surface after falling in? I'm sure it depends on what they are carrying, and if it's a insulated container, but it's got to be rare that they stay on the surface for long.

We've seen a massive steel off station Super Buoy (unlit), a few 55 gallon drums and a bunch of wooden shipping in the mid Atlantic... the super buoy would be bad if you hit it, but the other stuff shouldn't cause severe damage if sailing at cruising speed.

Has anyone seen much else?

Matt

jmh2002 30-11-2019 12:16

Re: crash bulkheads on production boats?
 
Yeah containers issue seems to be somewhat of a constant, probably just more reported these days.

But the amount of other debris seems to be on the increase.

I also think that cruising boats hit objects more often than they realise especially in rough weather when the object couldn't be seen and there is a lot of noise anyway.

I for one have found scratch/abrasion type marks on the hull after passages that weren't there before. Plain old sea water doesn't do that...

But I'm also not trying to start a panic here, only just trying to reinforce the notion that the amount of debris is getting worse and boats are starting to hit objects much more often.

I think it should be a consideration for the future.

:boat:

Discovery 15797 30-11-2019 12:42

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by jmh2002 (Post 3026497)
Despite the warm fuzzies that author Charles J. Doane wishes to bestow on us (which mostly seems to be along the lines of 'ah, don't worry about it...') the anecdotal evidence seems to suggest (to me at least) that the odds are changing, quite rapidly...

One can even see it, by the much larger amount of 'stuff' - be that rubbish, junk, debris, etc, that now floats by us much more regularly at sea

:boat:

Interesting...I did not get that from the article. He clearly states,

"This is a risk you take when you sail offshore, and you cannot reasonably expect anyone to obviate it for you. You can obviate the risk yourself by keeping a good watch..."

Anecdotal evidence is just that...unreliable, hearsay, data-less. Just as with modern news...the hyper-emotional and overly sensationalized speculative viewpoints portrayed sometimes do not reflect reality or data backed by actual statistics. But, they tend to be the stories that stick in our minds the most, and paint a picture we want to see regardless of the facts.

I see flotsam and jetsam all the time. I've hit more partially submerged objects in Puget Sound than in Pacific crossings, or the South China Sea. I am not arguing flotsam and jetsam do not pose a danger, however, statistically sailboats suffer greater damage running up onto a reef than being holed mid-ocean by a lost container.

Statistically...the vast majority of sailing is inland waters and near coastal, and rarely night passages. Thus, manufactures who want to sell boats may conclude that water-tight bulkheads would significantly increase costs while providing very little value add for the majority of sailboat owners. (Obviously I'm speculating here since I'm not a boat manufacturer.)

On a recent passage from SF to Hawaii, USCG Honolulu sent out a hazard to nav warning on VHF of 2 FADs (fish attracting devices) that had broken loose and spotted earlier in the evening. About 2 hours later at about 23:00 local time I picked them up on radar and passed within 4 nm of them. These FADs are so much a danger to navigation they are specifically warned about in the Coast Pilot Vol 7. Also, on that trip I had a piece of 3' x 10' netting get fouled in my prop, and passed a mounted car tire, a plastic 55 gal drum, and a large black plastic buoy of some sort.

toddster8 30-11-2019 12:47

Re: crash bulkheads on production boats?
 
While not a “watertight compartment,” my small production boat does have a plywood crash bulkhead below the V-berth, isolating the forward-most compartment to about six inches above the waterline. (Well, the second-most. The anchor locker in the bow is entirely above the waterline.) I’ve often thought that it could use one aft, to isolate the rudder post. One could be added, but it would be a bit of a nightmare to gain access and re-route cables and ventilation hoses. On paper, it looks as if the settees and bunks along the sides could be made into water-tight cells to the waterline, but in practice, ventilation and utility routing act against that idea. And there are gaps at the galley, head, and hanging locker that would be difficult to carry through the idea.

In short - the boat could have been built that way in the first place, relatively simply. Retrofitting it could be a bit of a nightmare.

Hardhead 30-11-2019 12:49

Re: crash bulkheads on production boats?
 
Here's the helpful gist of it from the author:


"It also makes no economic sense for the shipping industry to equip the many millions of containers in service with special safety gear to protect a very small number of sailors against a tiny threat of harm."


There you have it - industry has spoken, and money makes laws.

sailon46 30-11-2019 18:39

Re: crash bulkheads on production boats?
 
My Bene 51.4 Cyclades has a bow chain locker with only access from outside at the bow,,totally enclosed. Behind this 3-4 foot box, there is the crew cabin also with an impenetrable bulkhead, that is another 10 foot enclosure. The stern also has a bulkhead with a space of 6 feet to the sugar scoop. This design is duplicated to all the Benies oceanis etc.
FYI Ernie on the Mary Jane

Red Sky 30-11-2019 19:10

Re: crash bulkheads on production boats?
 
Anchor locker and holding tank are forward of the water-tight bulkhead and an above waterline dam forward of the rudder post on my Caliber 40LRC.

Dockhead 30-11-2019 21:17

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by Lake-Effect (Post 3026420)
Our boat has a watertight, isolated lazzarette :wink:. Sort of like an airbag on a tricycle.


Nonsense. That is a Very Good Thing. :thumb:

KWISPEL 01-12-2019 03:38

Re: crash bulkheads on production boats?
 
There are also boats like the ETAP 38i, completely 'unsinkable' due to its double hull filled completely with closed-cell foam. The foam is completely attached to the hull (part of the structure), and still dry after 25 years. Even bigger bonus from the foam is that there is then no condensation (well insulated, bone-dry bilges), and also greatly reduced noise from outside (including from waves slapping against the hull). I love this boat, and have never understood why no other brands make boats in this way, and everyone is dealing with mold and condensation, etc. in the winter.
Greetings from a warm, dry boat with ice on the deck :)

edmundsteele 01-12-2019 05:39

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by S/V Illusion (Post 3026149)
Given many people routinely want easy access to these spaces (forward cabin, main cabin, engine, etc...), they are routinely left open. If you’ve ever tried closing a door against the flow of anything large enough to sink a boat, it seems like a “feel good” but futile option.

It isn’t as much a matter of cost as it is practicality.

When on passage with our Amel, we would typically leave the door to the forward cabin open so that we could easily access the head. At sunset, we switched lifejackets to those with a strobe and harness, we switched instruments to night display settings etc. and we closed the water-tight doors. Our rationalization was simply that in a night-time collision, it would be easier to avoid confusion if this had already been done.

noelex 77 01-12-2019 06:35

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by S/V Illusion (Post 3026149)
Given many people routinely want easy access to these spaces (forward cabin, main cabin, engine, etc...), they are routinely left open. If you’ve ever tried closing a door against the flow of anything large enough to sink a boat, it seems like a “feel good” but futile option.

It isn’t as much a matter of cost as it is practicality.

In our case the waterproof door works fine as a normal ordinary door. It has four stainless steel dogs, but these all close with a single lever. So the door can be be left closed without restricting easy access to the owners’ cabin

In the event of an emergency, with the door open it would take a great deal of water pressure to stop a frightened sailor closing the door and any water pressure from the most likely forward direction would be helping close, not open the door.

We can float with two of our five compartments flooded so in the very worse situation once the water level has stabilised, the door could be closed and the water could be pumped out from the undamaged section.

It is hard to allow for every contingency. Nothing is foolproof and our system is arguably overkill, but I think your suggestion that it is a: “feel good but futile option” shortchanges the safety benefits.

thinwater 01-12-2019 07:43

Re: crash bulkheads on production boats?
 
Quote:

Originally Posted by Dockhead (Post 3026330)
If you wanted the Kevlar for its structural properties, then perhaps it would make sense to put it in an inside layer. But remember resisting an impact may also involve preventing PENETRATION and a hull breach, and that is what the Kevlar is for, at least on my boat.




I had a Kevlar honeycomb boat that was impacted. The outer skin collapsed and cracked and the inside held quite easily in tension.



Yes, using Kevlar on the outside for impact is poor engineering. Abrasion I get.


All times are GMT -7. The time now is 15:52.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.


ShowCase vBulletin Plugins by Drive Thru Online, Inc.