Add a water tight bulkhead?

[SeaHusky]

My planned refit has turned into a full renovation.
As I removed more and more of the interior woodwork and old lining I found that I may just as well do it all now and be done with it
rather then do a temporary fix up and continue next winter.
I also found that several bulkheads, that I had planned to redo the joint to the hull, are less work to completely replace than to mend and fix.
This leads to something that I have had in my mind for the future but need to consider doing now or not at all and that is a watertight bulkhead.
I have read that 90 % of leaks due to collisions are on the bow part of the hull (you sail into something in the water).
It then makes sense to have a water tight bulkhead somewhere in the forward half of the hull.
My idea is to make the mast bulkhead completely seal against the hull from the bilge up to the level of the bunk tops.
I would then make the doorway rounded at top and bottom leaving a rather high threshold, low enough to step over without to much trouble yet high enough to hopefully be above the waterline when the part forward of the bulkhead is full of water. It must also be strong enough to take the water pressure.
This is not meant to stop the boat from sinking but to buy some time to fix the problem. 

What are your thoughts on this?

[SailorTom]

Having spent many formative years in the USN, I'm all for water tight compartments! What's not to like?? I'd go a little farther though and subdivide and make watertight the volume under the V-berth and the chain locker. The problem is a fully flooded forward cabin is going to be very heavy. How would you pump it to clear it once the hull had a temp fix? Basically the more watertight areas the better!

[CapnK]

I've done a *lot* of thinking on this one as I considered how to re/build Katie best. My ideas:

I think you'd want to make your bow stowage areas project above your at-rest waterline, the higher the better to a point of retaining usefulness. Also, if they crossed centerline, divide them along that line. Then compartmentalize them at least 2 or 3 to a side for this size boat, so that only 1 or 2 smaller areas could flood even if you had a large/long gash, on the order of several feet (!!!). Make them top accessible (perhaps just while at sea, for convenience at anchor?), and that should be a somewhat seal-able access - if not watertight, then at the least tight enough to slow an influx of water. Having them be able to screw down against a gasket, for instance, and quickly even w/out power tools, while in the dark, and being tossed about (pre-drilled/tapped, large diameter wing screws or similar, perhaps)...

Pleasant thoughts, eh? :D

Also, plan the 'doorway' into the v-berth to be able to act as a cofferdam by tapering it towards the bottom, and having drop boards to fit located nearby that could be installed in seconds. Probably gasket the edges of these, and make them so they could be cinched down tight against each other with a light line and some small cleats or similar. That'd let you keep that area basically separate from the main cabin.

Last, watertight access through that bulkhead for a hose led to your large capacity manual bilge pump so that you can empty what's up there quickly and frequently until 'patching weather' comes along. Make sure there's a good strainer system on the intake.

Then, hope you never, ever have to find out if you can win a race with in-rushing ocean water. :)

[KB1973]

I like the idea of water right bulkheads. I believe Roger Taylor of Mingming 1 and 2 has sealed water compartments with flotation added. From what I have read he is very addament about these things in his boat design.

[SeaHusky]

Hi KB1973!
I have also read all of Taylors books and am partly influenced by him. I thought about buying a GRP Folk boat and setting it up like MingMing but that may be for the future. Taylor has learned the hard way and has come up with the solutions that suit his style of voyaging without compromise. His style however has more in common with space flight than cruising. He launches his "capsule", orbits the high arctic for a couple of months and then reenters land safely. How would MingMing look if he not only passed Bear island but also wished to go ashore there? Anchor, chain, dingy, more anchors etc. The space for foam dwindles fast as you approach the needs for more cruiser like voyaging.
Sectioning and water tight compartments are a compromise that I am still looking at as I rebuild the interior of my boat.

[KB1973]

Yes agreed Seahusky. For a cruising vessel changes would have to be made for ground tackle, dinghy, etc. For someone crossing oceans his modifications make a little more sense. Every boat is a compromise on some area or another. Amazing that he gets 90 plus days of food and water on a 24 ft boat.

[SeaHusky]

When hiking you usually calculate around 1 kilo of food per person per day so that is 90 kg of food. "They" say that you need 2-3 liters of water a day but Taylor has found that he only needs 1 liter so that is another 90 kg. Stowed low as ballast and he gets a nice raised floor between the bunks. Matt Rutherford filled a Vega with supplies for a 300 day voyage...

[Norman]

I have been on a number of ocean going vessels, and the watertight doors have always reassured me.  They varied immensely from older military craft to modern cruise ships.

A water tight bulkhead at the mast, all the way up and across would be the best.  A high threshold step through door, with hammer in place wedges on both sides would be both adequately strong, and reasonably light weight.  That sealed space is a huge amount of buoyancy.

That level of positive sealed space would seem to be all you are likely to need.  Foam floatation takes up too much needed space, as I well know in my Macgregor.  The space under the V berth is full of peanuts, and the space under the cockpit has large rectangular Styrofoam blocks that use up more than half the space.

Even so, I am not unsinkable, as the outboard that I am using is 80 pounds heavier than the factory used for the demo, and I carry 4 anchors, plus 64 feet of chain.

How is your Dad doing?

[SeaHusky]

A water tight bulkhead at the mast, all the way up and across would be the best.  A high threshold step through door, with hammer in place wedges on both sides would be both adequately strong, and reasonably light weight.  That sealed space is a huge amount of buoyancy.

Since priorities have shifted from "perfect" to "sailable next season" the bulkhead is on the back burner but definitely possible later on. How do you mean with the wedges?
Mast bulkhead is there as is the mast beam so the next step would be the high threshold. Also the bilge is continuous from the fore end of the V-birth all the way back to just fore of the engine compartment so that would also need sealing off with some sort of bulkhead with a sea cock valve.


My dad is OK, thank you for asking!
Walking with crutches for short periods. Lots of pain but that is to be expected.

[Norman]

Make a rectangular inch square metal stirrup and mount it at the edge of the door.  To seal the door shut, drive a one and a half inch tall wedge in the stirrup.  The stirrup may be round material and more than 1 inch wide to provide a hand hold when not in use.  The wedges would be on lanyard when not in use.

For a large door, 2 or 3 on each side would be needed.

They were used on a small cargo barge that I visited, to seal the 4 or 5 sections of the cargo space, and were in the side to side bulkheads.  Very low cost, but effective.  All their parts were steel, and a hammer hung at each door, ready to use.  They were always dogged under way, and only opened when loading to allow crew to move from section to section without climbing on deck.

The wedge is flat on the small end to allow hammering back out.

[SeaHusky]

Thank you for the description but I think I need a picture or a sketch. I just cant picture in my mind what you are describing.