Through hulls on passagemakers ???

As Mike Johns states most boats flood at the dock. The flooding has nothing to do with seacocks or holes in the boat ,its caused by leaks in the system downstream.

Keel cooled refrigeration is simple , cheap and eliminates a 24 hour per day seawater issue. Well worth the additional cost to install.

A typical catastropic seawater evet is a minor gounding with a motorboat that drives the P bracket into the hull or tears out the stuffing box. keep the stuffing box in the engine room and waterproof box off the P bracket

 

Michael, i surely agree that Bracketing and the P shaft needs protecting also. Although there is no way to protect a boat from all hazards, it is wise to build a boat to handle those hazards. I love a full keeled boat with a skeg that holds the propellers shaft. Also a like the newer types of shaft seals that can absorb shock and are also much lower maintenance. If you happen to have a boat with the propeller shaft brackets mounted directly to a hull, and that hull is fiberglass, before doing major deep water cruising, i would sure reinforce those positions from inside with layering and bracing(if possible) and outside with layering. With the newer kevlar additives for glass now, it should be reasonably simple. I surely agree with you. I read of one guy who cruised successfully to the Med and caught a rope which wrapped on the p shaft. It ripped the bracket just enough to cause it the leak. Sunk in port. Ouch!!

 

"People talking about engine rooms with water tight bulkheads are talking about big vessels. Name me 1 boat under 20m built like this...."


Come on down to FL, our 33ftLOA . 90/90 has a collision bulkhead and 3 compartment subdivision.

Just takes time and thought, with a suitable application of currency.

"and my prop shaft is oil filled with seals on inboard & outboard ends."

Good idea ,,,IF its filled with bio degradable oil the Sheen Police require.

FF

 

thru-hulls on passage-makers..

Steve,

What you said is re-assuring somewhat...it does seem that there is generally what could be termed a neuroses about thru-hulls in the sailing community...I have wondered if this "complex" began a long time ago in the bronze age...or developed later say.....perhaps only after the mid-70's when builders started going with sea-cocks made with materials other than bronze...? just a couple of my thoughts for the group today...

 

My 1972 Albin 25 motor sailer has a water tight engine room. Actually it's an engine box, and currently I don't have an engine in it. But the ends of prop shaft and stuffing box are in it.

The box is comprised of a shallow pan and a hinged box cover with clamps. There is a molded matching flange and rubber seal where they join.

Is it completely water tight? Haven't tested it. The secret of remaining afloat is the ability to pump out faster than it leaks in. So, the tactic is slow down the ingress of water if you can't actually stop it!

 

Could anyone speak to whether an "all oceans" ratings, such as a number of smaller passagemakers have, has the requirement for water tight bulkheads, possibly fore, aft and, or engine room. Having trouble searching.

 

What Clasification Group bestows this "all oceans" rating? I've heard the term, but never encountered it professionally.

As you have been talking about Nordhavn's I looked all over their site and found little mention of any rating at all, and if I'm not mistaken only the big ones are built to MCA standards as an option, except for the 120 which appears to be MCA standard.

Any "all oceans" rating would I think only apply for insurance purposes, building standards are specified by classifications like MCA, Lloyds, RINA, etc.

Steve

 

This quote is about the design of the Bruce Roberts 43' Passagemaker. All of his are unrestricted, which is what i" These trawlers are designed in accordance with Lloyd"s for category 1 (unrestricted operating / sailing area)". Not sure where i got the "all oceans" but unrestricted is what i mean. I will try to find the author of my "any ocean" term.

 

If you plan to build to a standard like Lloyds, you may not like some of the products and techniques you will have to use to comply, not to mention the additional expense of the specific approved materials and inspections. While these standards make sense most of the time on larger vessels, some of them do not scale down very well.

These standards cover almost every area and aspect of the build, from scantlings to materials to placements. The structural fire protection standards alone, even for steel, require rigid adherence to a vary careful matrix of material and design all the way down to fasteners and their placement.

Also, I believe the Lloyds standards for a small sailing aux are not nearly as stringent as for a motor yacht. The Lloyds standards go back to the days when a yacht meant a sailboat, so their standards for sail cover a wide range of size just because Lloyds is so old.

It's good to be familiar with these standards, as they represent best practice, and it may make financial sense to follow a standard for value or insurance reasons. But for instance most of the Nordhavn's out there are not built to the MCA standard, and they offer it as an option on the larger models because its expensive to comply, and thats for a product that already costs big bucks.

Steve

 

I have long run my boats with all valves closed when I am ashore.
To this end I installed a simple sea chest on my current 12m mono sailboat.

I used a single oversized thru hull with a large strainer from which a pipe manifold serves for the few raw water needs I have.
Each feed has its own valve as well.
Valiants have a similar setup though a custom welded up manifold is used.

 

Impossible,--even if water went in the exhaust and through valve overlap and out the intake. If it was water tight the engine would not be able to breath, and if the air intake was outside the box then the you would have the problem above.

Wires, control cables, cooling intakes!!!

 

What small boat has high pressure air supply. Start the fire pump!!

But all unnecessary, a stand pipe raising just above the water line housing various cocks feeding supply needs.

If the top of the pipe was knocked of the boat would not sink.

A 2 inch cock on the top and you can stick a broom handle straight through the bottom clearing any debris without high pressure compressors.

Whats been omitted is ships have 2 sea chests so one can be shut down and cleaned while the other is in use.

But like some one said these Lloyds regs dont scale down well somtimes.

 

Frosty
I like your broom stick idea for clearing a choked seachest on a small vessel.
As far as fire pumps, a manifold allows a pump to be multi purpose. Some boats carry scuba bottles (hi pressure air).

I'm letting these photos of an albin 25 motor box base and its air ducts explain for me. All exhaust and controls, electric harness pass into base. These can all pass through seals, gromets or electrical stuffing boxes. Or as described on right side of designers sketch, through rubber bushes
cheers

 

Steve, your probably right in that it is not practical to scale Lloyd's Standards. I would, however, use a lot of the rules of thumb for structure as a base. Therein was my question about water tight bulkheads and engine room. If i'm going to the islands, where i'm only 50 miles from the nearest port, and the boat starts to sink, well just hop the dink for the next piece of dirt and letter sink! But, if i'm 1500 miles from somewhere, and 1300 more miles to somewhere, and if i could not keep her upright, at least if she would stay around for even a little while, that would be nice. But mainly, i'm thinking more in that the bulkheads are what seem to allow boats like Dashews, and others to claim to "hopefully" take a roll and stand back up. Here's to positive thought, smart ideas, and low budgets!

 

For those trans ocean passages: