Hogfish Maximus - 44ish sailing sharpie?

DR is Dead Reckoning or Deduced Reckoning. It is keeping track of your position between fixes as best you can by monitoring/recording course and speed and possibly predicted current sets. Some navigators call it estimated position EP if you include current in the calculation. In the days prior to GPS/Loran/Decca which give continuous fixing of position, you had time between fixes which was DR time. Typically ships sailing by the sun and stars took position lines when possible. A position sun-line say at 9 am can be 'run up' using your DR course and speed to another sun-line ( now a different height and different bearing ) say at 2pm. Where they intersect you have a "running fix".
If you do not have a decent fix for a bunch of hours or days because of weather, your DR might have a large error. You simply do not know where you really are. Approaching land, making a landfall in those conditions was scary to say the least.

GPS can have errors sometimes, or Charlie could have read it wrong. Fatigue??

GPS does not eliminate the danger but massively reduces it. People can and will plow into the shore from time to time, despite all the advantages we have today

 

Alan,

I'm curious how your external steel ballast plate worked out? Phil Bolger specified external steel ballast plate on some of his sharpies, bolted through the plywood hull and into support timbers. My concern was that no matter how well you galvanized, or epoxied, or painted the steel plate, eventually you would get some nick in the coating that would allow rust to start. And once rust started and got on the top side of the plate, between the plate and the wood hull, you'd never be able to stop it. Since rust occupies more volume than steel, I would think you'd have a problem with the expanding rust pushing up against wood.

Another problem that I imagine is that the sealant you use to between wood hull and steel plate would make it very difficult to remove the plates should you ever need to repair or replace them -- unless the sealant failed, in which case you might not have even bothered using it in the first place. Did you use galvanized bolts or bronze bolts, or??

 

First I should explain my boat building methods are crude, cheap, and fast. This was influenced by early experience in NZ where a boat might be competitive for only one or two seasons, and therefor there was no need for it to last longer. This influenced material choice.

The ballast on this boat had steel sheets each about 2' 6" wide, and 15' long, rough cut with a torch. These were to be placed flat on the bottom, each side of the wood CB. After drilling a large number of 1/2" holes, scattered across them, they were 'Cold Galvanized'. This process, probably illegal now, involved making the steel 'bright' using a steel wire brush in an angle grinder, then scrubbing (with a long handled brush) the resultant surface with a chemical that created noxious fumes, and steam, probably caustic soda, or something similar. The "paint" a compound containing zinc, was then applied using another long handled broom, including the drilled holes etc. This etching changes the steels surface such that it will accept, via covalent bond, elements contained in the 'paint'. This process is similar to the process I helped develop for painting cars many years later. The "paint" penetrates several molecules into the surface of the steel, and should protect it even if it is scratched.

The boat, with its full plywood bottom, was lowered onto the steel sheets, using jacks. The steel was covered with a bituminous compound (I think) that smelled of tar for sure, that allegedly never solidified, i.e. remained pliable for its life. It was used, if memory serves, to join cement or ceramic pipes underground. It stuck, but was not an adhesive, and did not become brittle like real tar.

Holes were now drilled up through the bottom, using the steel as the template, through the plywood bottom. 1/2" hot dipped Galvanized carriage bolts dipped in the aforesaid goop, were driven up into the boats interior. Where necessary, timbers were added to back these bolts on the inside, and these timbers arranged as frame, or stringers, as necessary. Galvanised were used as no chance of galvanic corrosion. Drilled holes were 'squared' with a cold punch so the bolts might grip.

I only owned/operated the boat for a season before moving on, leaving it to a colleague who lived their. We pulled it after a season, and the bottom was still perfect, though the front of the CB was quite scuffed from impacts. We repainted, and I moved on. I heard a year or more later the boat was still well, and no work had been performed on the bottom, but then I lost track, so no long term news.

I do not suggest this method, it is probably illegal and officially toxic now, if it wasn't then, 40+ years ago.

 

Knowing ones position, and being able to do something about it are two different things. As I usually sail with a full racing crew, this is rarely an issue, but rescently I have 'cruised' and discoverd a completely different case. Being in a deep keeled boat, with a faulty motor, no wind, and a tidal set toward the coast, is no joke. Coast Guard recommendation in this case is to hang the anchor over, with all available chain/line extended, attaching the bitter end to the mast or something seriously solid, and wait.
We didn't, but a breeze came up with the dawn, and so were able to sail away, but it was a scary situation with limited crew on board.

 

Thanks for mentioning this process. I'm betting it may be described herein: https://books.google.com/books?id=6...epage&q=cold galvanizing caustic soda&f=false

Free for PDF download.

Of course, like that one fellow who'd mix some glycol back into his store brand low-VOC paint to get a smooth line this is something I'd NEVER do.

Honest.

PS: they sell "cold galvanizing" paints but these are probably NOT nearly the same process that you used.

 

Thanks for the description, Alan. I've never heard of cold galvanization. Perhaps it is something like this product. If you can believe the hype it sounds pretty good.

RUST‐ANODE® AND RUST‐ANODE® PRIMER TECHNOLOGY

FREQUENTLY ASKED QUESTIONS (pdf)

Looks like you could use the stuff to re-galvanize your own anchor, maybe even an anchor chain?

 

Thanks Gilberj,

I do know in English what Dead Reckoning / Deduced Reckoning is, just the meaning of the abbreviation DR didn't pop up in my mind as abbreviations are always more difficult in a foreign language then in your own.

In Dutch it's called Gegist Bestek.

I was thinking, maybe the term "Deduced Reckoning" transferred into "Dead Reckoning" because of the many deadly mistakes that were made by it in the days before the invention of the marine chronometer, in which time it was impossible to make a good determination of longitude on a long sea voyage. That's also the history why in Dutch it's called "Gegist Bestek" which literally means "Guess Reckoning", which term is still appropriate if you can't get a decent fix for a couple of days because of the weather.

According to his account Charlie had a Garmin 72 GPS, which is an handheld GPS, so I think he had to transfer his position to a chart to see the surroundings of his position, maybe that's where he went wrong . . ? ?

Garmin GPS 72™​

- - ​

 

Here's a Dutch link to a "cold galvanizing" zinc coating that also contains 96% zinc like in your link, maybe you can read it through a translator . . ? ?

 

Thanks for the links, Angélique. Here is a link to the USA site for Zinga. Could very well be the same type of process I found above.

 

I think 'dead reckoning' for 'deduced reckoning' is simply an ironic pun, or is it a malapropism......

 

If it wasn't for dead reckoning I'd have never seen parts of Tarrant, Rockwall and Collin counties here in Texas ... none of which have ever been between home, work, or where I've gone to school.

Aside: I've long suspected that in-car GPS units were the work of a man sick of his wife asking him to stop and get directions.

 

Yes, that's most likely the case, but then the funny or ironic thing is it also fits very well in the historic context of the times before the marine chronometer . .

 

I'm not sure which one you mean, I guess the last, anyway here are a couple, in metric tons I believe...

- Botter Bössel in post #190: 12.5 tons (pdf specs)

- The Yawl in post #238: 1.95 tons (pdf specs) - The specs say 1.95 m³, I guess that's in fresh water.

- Pierius Magnus in post #244: Schoonerman info, ± 12 tons and can hold a couple more till she sits on her design waterline.

 

During my USAF navigator training, we were told that "dead" reckoning is actually "Ded" reckoning, the pronunciation causing the confusion in spelling.

 

Another interesting blog by Chris Morejohn regarding his many boat designs, including the Hogfish series.

The design evolutions of a SHALLOW MINDED SAILOR WHO THINKS DEEP SEA THOUGHTS


HFM dreaming of a big square head mainsail and code zero