Yacht Design - ballast considerations.

General Sailing Talk
Post Reply
User avatar
Raya
Posts: 314
Joined: Sat May 05, 2012 4:25 pm
Investigator Boat Name: Tme Out
Location: Gold Coast

Yacht Design - ballast considerations.

Post by Raya »

I came across this extract in the book listed below. I couldn't help but think that the author had the Investigator in mind.

PRACTICAL BOAT-SAILING: A Concise and Simple Treatise
BY
DOUGLAS FRAZAR,

FORMERLY FOURTH OFFICER OF THE STEAMSHIP "ATLANTIC,"
MASTER OF THE BARK "MARYLAND," AND COMMANDER
OF THE YACHT "FENIMORE COOPER" IN THE
NORTHERN SEAS OF CHINA AND JAPAN.
Copyright, 1879


"Nearly all yachts that are ballasted, when filled with water, will sink; and there have been many ingenious ways devised to prevent this, so that, in case a yacht should be swamped, i.e., completely filled with water, she would yet float, and make a sort of life-preserver to the occupants, and not go to the bottom, and leave them struggling on the surface.

A very ingenious and yet cheap way of obtaining this result is to have built into the wings of the yacht, under the floorings, and in every conceivable place that is out of the way, empty tin or iron six-pound powder-canisters, that seal hermetically, sufficient in number to overcome, by the air they contain and the natural buoyancy of the wood composing the yacht, the weight of the ballast, or the tendency of the same to sink the yacht when filled with water. It will not take a great number of these canisters in quite a large yacht of medium model; for, although the yacht will sink without them, it does not take very much of this confined air to turn the scale, and make it float.

Some yachts are ballasted with lead; and this, if it were not for its cost, is a prime ballast, taking up less space than any other. And some care not for the first cost; for, as is truly said, it is a marketable article, which does not vary much in price: and, even if it should cost quite a sum to ballast one's yacht with lead, it is so much cash on hand, and can always be taken out and sold at a moment's notice. Besides the different kinds of ballast that have been enumerated, there is also the living ballast, that is to say, human beings, whom one can place in different parts of the yacht to trim her in different situations. But this kind of ballast is mostly used in racing, and even then is sometimes apt to "get out of order," and not "work well;" and the writer would advise one to stick to iron, lead, gravel, or sand as superior."
Ray
Investigator #39
User avatar
Ozzie
Posts: 1621
Joined: Wed May 27, 2009 1:07 pm
Investigator Boat Name: Spritzig II
Location: Lake Macquarie
Contact:

Re: Yacht Design - ballast considerations.

Post by Ozzie »

Interesting stuff Ray. I recalled reading on here that someone found water in their airtight compartments

Research turned up

viewtopic.php?f=4&t=492&p=2390&hilit=ai ... 89d8#p2390

Cruiserpete was concerned that these compartments had the potential to leak. Now I’ve only had Spritzig II for 15 years so you can’t rush these things :) but I’ve always been going to remove a screw from the cockpit step and poke a bit of stiff wire down there to see if it hits anything, like floatation foam which many years ago someone said was an option on the 563.

Airtight compartments are a terrific idea in principle but need to be ....well, airtight to work..hence the float foam option on the 563

I suppose small gaps in seams would take a long time to let enough water in to be an issue but it’s something I occasionally wonder about.

It’s interesting that you don’t need much air to float a boat. I recall was it mythbusters proving that the scene with the upturned boat in pirates of the Caribbean with the occupants walking on the sea floor was bogus because if there was enough air to breathe the boat would stay on the surface.

YouTube have this but think MB also did a segment
https://m.youtube.com/watch?v=MRQABTtYJZ4

Those of you ancient enough will know that movie filched the idea from “The Crimson Pirate” (1952) with Burt Lancaster and Nick Cravat in the Depp and Bloom roles. They also defied Archimedes Principle. :shock:

Yes, I’m a fountain of $#i+ 8-)

Ps anyone tested the airtight compartments for seal?
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
User avatar
Ozzie
Posts: 1621
Joined: Wed May 27, 2009 1:07 pm
Investigator Boat Name: Spritzig II
Location: Lake Macquarie
Contact:

Re: Yacht Design - ballast considerations.

Post by Ozzie »

I recall my mate with the Court750 saying he did not trust the airtight compartments in it so over the course of a year put every plastic drink bottle he could get, in through an inspection hatch with a screw down lid that he installed. I think it’s probably something that wouldn’t hurt on the 563 but I’m too far along in my ownership to care probably.

I read a story about a guy who when doing long sailing legs between Aus and NZ for example would inflate three tractor tubes inside his yacht. Apparently he’d calculated that it would keep it afloat if holed and he didn’t need much interior space when in transit only access to one quarter berth and nav station.

By the way the whole movie of “the Crimson Pirate “ is on iTune. I’m just about to rewatch it after 30 years ....better than bloody PIrates of the Caribbean. ;)
Ozzie
Investigator #143 "SPRITZIG II"

The Mariner - “It’s too strange here. It doesn’t move right." ...
Enola - “Helen said that it’s only land sickness."
Waterworld (1995)
Post Reply