C A Thayer Hog In Keel

[Dave Fleming]

Here is a photo of that hog. I had occasion to peruse a fairly new book on the Pacific Cod Fishery and there is a photo of the Thayer in dry dock during that time that clearly shows the very same hog. She worked that Cod Fishery for some years and I could find no record of that hog causing any problems.

Me, I'd leave it.

http://www.imagestation.com/picture/sraid111/p170c01167a2c409ec3871ea9f5ea1f0b/f90e6b13.jpg

[ 04-11-2004, 12:27 PM: Message edited by: Dave Fleming ]

[Paul Scheuer]

This one shows it to me. Did I read that it's about 18 inches ?

http://www.bay-ship.com/Media/th2_7013.jpg

[Dave Fleming]

So they say.

[Paul Scheuer]

One of my old references says that hogging occurs as a result of the lack of use, where the wave action would provide more lifting in the ends, and static storage without a load that would provide more loading in the more bouyant center.

Any idea how the keelson is constructed ?
How bout the frames, etc ?
Does the deck show a coresponding hump ?

How long has she been in static storage/dispay ?

[Paul Pless]

Someone recently posted that Bolger had design a ship with a hog built into it? Why?

If the hog in the Thayer were removed, could it be prevented from coming back? How?

Does the hog affect the sailing characteristics?

[RGM]

For those that are interested in how larger wooden ships are/were built might I suggest you find a copy of "WOODEN Ship-Building" by Charles Desmond, published by Vestal Press, ISBN 0-911572-37-6 and take a look. Loaded with great text, photos and sketches. I think it's about $25. I believe the WAWONA has a 2 foot hog, or there abouts.

[John E Hardiman]

Hog in a ship is caused by having the vessel too light on her lines. It is very prevelent in wooden cargo vessels that sit for long times without any cargo.
Because the ends have a higher structural weight to buoyancy, they tend to sag. Conversely, midships has more buoyancy than structural weight (especially in way of the holds) so the middle is pressed up. The hogging is a natural result of the keel material attempting to minimize internal stress. Hogging reduces the internal stress on the keel (by lowering the sectional modulus of the hull) at the point where the keel has the highest shear stress.
You take hog out by the same way it got there, pressing the keel back down to shape along its length over a long period of time (like they did with the USS CONSTUTITION ). To keep hog out, you have to ballast the ship down to mimimize shear stress midships. But this has it's own problems for historical ships because much more of the hull is immersed.

Hogging is not a problem for wooden vessels only. Because of the weight to buoyancy distribution, it is possible to hog or sag a metal or composite hull also. And with supertankers or ore ships, you can even fail the hull girder with poor ballast management.

[mmd]

Paul S., I can't answer your direct questions about the Thayer's construction and situation details because I am not familiar with the ship. Maybe Dave Flemming can help you on those questions.

Hogging occurs in boats when the mass of the unsupported structures in the ends causes to hull structure to distort in an attempt to equalize the internal stresses. The greater the usupported mass, the more likely the vessel is to hog. For this reason, vessels like the Bluenose with great long overhangs are very susceptible to hogging. Also, old sailing ships when unladen, such as the Thayer, have a fair amount of structure hung out over the water without any hull below to support it. A recipe for hogging.

Yes, there should be a corresponding hump in the deck, Paul P. I believe I can detect a wonky curve in the sheer stripe in the picture of the Thayer on the transport rig posted by you.

Let's play "experiments of the mind" again - a favourite method of mine. Given that a hull is fundamentally a box beam and therefore should behave in a somewhat similar manner, let's experiment with hogging stresses. If you take two long, narrow cardboard boxes (say, boxes that 48" fluorescent bulbs come in) and balance them crossways on a plank, it is analagous to a hull floating on it's centre of buoyancy. Place one box centred on a plank that is 40" long (85% of hull LOA, similar to a loaded boat with short overhangs lying deep in the water) and place a one-pound weight at the extreme ends of the box (to simulate the anchors, windlasses, and bowsprit & rigging at the bow; and rudder, steering gear and transom at the stern), and place the similarly loaded second box centred on a plank only 32" long (65% of hull LOA, similar to an unloaded boat with longish overhangs floating high in the water) to simulate a hull with extreme overhangs above the water. All set? Now lets compress a few years of wharfside inactivity into an hour. Get a plant sprayer and mist the box with water - just enough to dampen the boxes' surfaces - every ten minutes to simulate the occasional rainshowers and permanent dampness that the ships' hull exists in. After an hour have a good look at the shape of the boxes. The short overhang box will have sagged a bit at the ends, but because of it's good longetudinal support, it should be in fairly good shape. The box with long overhangs - hence poor longetudinal support - is likely to be a disaster, with it's ends distorted and collapsing. Same box construction and strength, same loading, just different stresses on the structures. Also note the difference in distortion between the bottom and top panels of the boxes. The bottom panel and the bottom edges of the side panels absorbed most of the hogging stress, but the top panel moved, too. This mimics the Thayer's extreme hog at the keel, but much less hog at deck level.

Can the hog be prevented from returning, if removed? Yes, but nobody would like the solution. The interior longetudinal structure would have to be significantly strengthened by adding stuff like complex metal truss systems or some such monster that would destroy the original interior. Or, she could be placed on the hard and braced externally. Or she could be forced back into shape and trussed and stressed to retain her new shape, but such stresses would probably tear her old hull fabric apart. Same as trying to get your old granny back to looking good in a bikini, it could be done, but the cost and stress on the old girl would be enormous. It would be best to let her enjoy her final years spruced up with a new dress and make-up, and only enough surgery to enable her to get around comfortably.

How does an extreme hog affect her sailing ability? Two answers; one minor, one major. The minor one is that the unfair run of her buttocks caused by the hog will have an imact on the resistance to her passing cleanly through the water. The faster she goes, the more this becomes apparent. But it is unlikely to account for more than a knot or two in actual speed, so it is a minor impediment. The major effect is that the hog is indicative of a weakened backbone structure. How much weakened is pure conjecture, but a prudent captain would not want to fly every rag including the galley dishcloths in a fresh breeze for fear of breaking something. Hogged boats are generally weak in their backbone, and stressing them will often cause garboard planks to break their fastenings, caulking to fail, and keel seams to leak. Sometimes, when under stress from the rig, the backbone will straighten under the load, causing the rigging to go slack allowing the spars to move about enough to put load where it shouldn't be and fail. And having a fore-topmast come tumbling down would put a dent in the most optimistic sailor's day. ;)

(EDIT: Dammit, John H., you had to get in before I finished typing, and be more eloquent to boot, too!! :mad: :D

[ 04-12-2004, 04:10 PM: Message edited by: mmd ]

[Alan D. Hyde]

Here's a link to a discussion about the diagonals in the U.S.S. Constitution:

http://americanhistory.about.com/library/prm/blbostonsancientmariner2.htm

***

Alan

[ 04-12-2004, 04:57 PM: Message edited by: Alan D. Hyde ]

[imported_Conrad]

Nice trailer it's sitting on in the second photo. I wonder what they pull it with? ;) :D

[Paul Pless]

mmd and John,

Thankyou both for the excellent explanation of why ships hog. I've always wondered.

paul

[Paul Scheuer]

RGM: I've got the Desmond book reprint. I especially like the table of Dimensions of Parts For Ships Now Under Construction (1919).

A 200 by 38 ft, 900 ton vessel - Keelson 16 x 40 ! with a 16 x 40 Rider Keelson.

[Concordia..41]

Same as trying to get your old granny back to looking good in a bikini, it could be done but the cost and stress on the old girl would be enormous. It would be best to let her enjoy her final years spruced up with a new dress and make-up, and only enough surgery to enable her to get around comfortably. :D

Thanks both Jim and mmd.

[Jack Heinlen]

It's interesting that there is very little hog apparent in her shear. I think I can see a little powder horn forward, but almost all of the keel hog is absorbed by the lower planking.

I haven't followed this story, but such hog is often defacto built into the hull over years of replanking. I say, leave it. Like I know? :rolleyes: smile.gif

[Paul Scheuer]

The sheer stripe would have been an easy fix. If the hogging doesn't appear in the deck, it might mean that someone has "fixed" the hog by adjusting the vertical bracing internally. (shudder)

[RGM]

Paul Scheur, glad to hear that you have a copy. I think it's a great book for any wood boat junkie to have. Besides detailing alot of the heavy construction there are nice sections of the book devoted to joinerwork, forces that affect a hull, masts and spars, joints and scarphs, etc. I could go on here but I'll leave the rest of it for others to read. It's a good addition to any wood boat library. It's also important to remember that these vessels were generally considered disposable! They were never intended to have long service lives. Excuse me for now, I've got to run up to Home Despot and pick up a couple 16"x40"x60' timbers.

[ 04-13-2004, 11:24 AM: Message edited by: RGM ]

[Andrew Craig-Bennett]

I simply do not understand why historic ships, maintained afloat, are not ballasted sufficiently to eliminate the hogging stresses caused by the weight of the ends. After all, the ships were designed to be laden, not empty.

Can an expert enlighten me?

[Alan D. Hyde]

Paul Scheuer and RGM, speaking of books of that era, have either of you read any of the Felix Reisenberg books?

Alan

[Dave Fleming]

***NO*** expert but, more than likely it has to do with being musuem exhibits vs: working sail.

Bureaucrat museum type: 'make sure all the trash in the bilge is cleaned out so people can see the structure of the vessel'.
Repair yard cleans out the vessel stem to stern and sends it back to the museum site.

What also might affect the Thayer is where she lies 7/24/365. A basin not too far from the entrance to San Francison Bay. The basin has notorious tide surges and almost constant on shore winds plus the fact the location is part of the outlet to the sea for the Sacramento River as well as several smaller rivers ie: Petaluma and Napa. The bluffs that anchor the Golden Gate Bridge act as funnels for that northern part of SF Bay. Witness the many photos of sailing boats both racing and cruising types. Sails full as they traverse the area. The Hyde Street Pier, site and the moorings for the vessels belonging to the San Franciso Maritime Mueseum, including the Thayer, Balclutha, Alma, etc., form the east side of that bulkheaded basin. In the many times I have visited there, the vessels are constantly working and responding to those factors.
Thayer is a tired old working vessel. Saw plenty of hard use as a lumber schooner, worked the Alaska cod fishery and coastwise trade. To me it is remarkable that she along with the scant few of other vessels of her era or earlier are still around!

What no one has mentioned is yet another big problem.
For as long as I have been visiting and working on her, the Thayers frames are in terrible condition. In fact last visit, about a year ago, I opened up one of the inspection ports to the bilge and a considerable number of frame ends abutting the keel were rotted away. In some cases as much as several feet was missing!

In My Opiniionated Opinion, the National Park System has done a terrible job with the SF Maritime Park vessels. just go to my Imagestation album on the WAPAMA to see the worst of the worst.
WAPAMA is hidden across SF Bay in a flooded drydock in a defunct WW II shipyard sitting on a barge and has been like that since the 1970's.
Frankly the private San Diego Maritime Museum has done a better job, with scant resources, for their vessels than the federal gov't has done with all their resources.
I am aware that the same yard that is doing the Thayer work did a "redecking" and hull plating repair in the Balclutha but that was several years ago. Again, IMOOP, the Thayer needed the work done before the Balclutha. In fact it was not a FULL redecking on the Bal.. When I visited her afterwards I immediately saw that the waterways were the ones we, the Anderson and Christofani yard including moi, replaced back in the 1960's. How could I tell easy. We all put our initials on the waterways in some semi hidden spot. I found mine easily. The original waterways were full 4 inch TEAK!
( I made a couple of nice boxes for some of my shapening stones out of chunks of that Teak)

The replacement ones we made were 2 inch Douglas Fir with an overlay of 2 inch Teak. I dunno the actual reason for the lamination but, could have been money or scarcity of full 4 inch Teak at that time. No matter we glued up the laminations with literally gallons of Weldwood Plastic Resin Glue. State of the art in those times. I do recall we wiped down the surface of the Teak with Acetone before the glueup. With several men slathering Acetone on the Teak in that mill shed we got a nice buzz going. Had to go outside and get some fresh air frequently during the process. We used dishmops to slather the Acetone on the Teak and clean shop rags with wipe it down with.
Probably got big holes in my liver from that!

Photo from Imagestation album showing Wapama's Stbd.bulwarks.

http://www.imagestation.com/picture/sraid11/pa3e4800cc58ab298491e6254438b235f/fe101208.jpg

[RGM]

Alan, can't say that I have read anything by Felix Reisenburg. I may have looked thru one by him though while at a bookseller. I'm a hell of a browser ya know.

[Oyvind Snibsoer]

Hogging occursin non-cargo ships, too. The old wooden minesweepers of the Norw. Navy had hog in their keels. When they drydocked them, they would assemble a crew of divers, and we would swim around and place wedges under the keel when they had pumped out enough water from the dock so that the ships had settled on the blocks fore and aft.

These were operative vessels, and would usually have their tanks filled up and carried the equipment they were designed for most of the time.

http://www.knmalta.org/bildearkiv/tilkai/bilder/pic02.jpg
The last remaining vessel of the "Sauda" class - KNM Alta, now preserved by a museum ship, owned by the Norwegian Armed Forces Museum and maintained and run by volunteers. The ship is maintained as a fully operative minesweeper, and can at short notice cast off and commence minesweeping operations. These ships were based on the same US design as Costeau's "Calypso", BTW.

I served on board a sister ship, the KNM "Utla" for a short period. The KNM "Alta" had at that time (1987) been refitted as a mine hunter. The ordinary mine sweeping equipment had been removed and replaced with a decompression chamber, an ROV and sophisticated electronic sensors for mine detection. AFAIK, she was equipped as a mine hunter until she was decommisioned, and was then refitted with the conventional mine sweeping equipment again when she was converted to a museum ship.

[ 04-14-2004, 09:30 AM: Message edited by: Oyvind Snibsoer ]

[Paul Scheuer]

No diagonal steel strapping in a mine sweeper, right ?

[Oyvind Snibsoer]

Hardly any steel at all smile.gif They even had bronze anchors :eek: The best part about being on these ships was the lack of rust to scrape and paint. Of course, there has to be some steel in the engines, anchor rode, sweeping cables etc. This is compensated for by a big degaussing coil that is run around the inside of the entire hull. Mine sweeping is a boring, unglamorous, and highly dangerous business. Being assigned to the coast guard was a lot more fun, much more comfortable accomodations, and a more meaningful service, too, IMHO.

[Paul Scheuer]

I hope I'm not getting this thread too far off the track. My first ocean voyage as a teen was on a wooden MSO out of Charlestown SC. I was impressed by the sweeping operations demonstration. The crew claimed to be the last of the USN's "iron men on wooden ships".

Another memory from that era was a photo book showing the last days of the Lake Schooner Age. One image that stuck in my mind was a picture from about 1914 showing what was then the very old Annie M. Peterson, (built 1874) being worked right up to her death, as a lumber barge, stripped of most of her spars and bowsprit. As I look at the picture now, there is no hog.

[mmd]

As can be seen in the picture below, the Annie M. Peterson is somewhat short-ended, so the amount of unsupported overhangs is minimal, Also, if she worked all her life without long periods of unladen inactivity, she would have spent little time riding high in the water which, as was mentioned previously, is conducive to hogging. There are other factors which bear on a particular hull's tendency to hog, such as method of construction, species and quality of timbers, scantlings of longetudinal strength members, etc.

Why do some ships hog and others don't? As usual, the standard naval architect's answer will be, "It depends". :rolleyes: :D

The Annie M. Peterson:

http://www.geocities.com/huronislandlighthouse/picture_ship_peterson.JPG

[Jack Heinlen]

I apprenticed in Bath. One of the places I worked was at the Percy and Small Shipyard, in Bath, ME. They weren't doing much shipbuilding there, museum owned, a pinky I think still is the flagship of that museum. 'Bowdoin' was on the ways, and ahead of her was 'Seguin', a tug, which I'm pretty sure was broken up--not enough money. But that shipyard, during the early 20th, built the largest wooden vessels ever. 400 ft schooners for the lumber and coal trade up and down the coast.

It was an honor to be a small part of it, even though its heyday had passed. It's now the main site for the museum, but when I was there they'd just acquired it, and it was a time capsule. Rbgarr will have some stories.

Looking at the pictures. The Wyoming, I believe the largest wooden vessel ever constructed, had a keelson of multiple timbers which stood seven feet tall. She ended on a reef in the Caribean if memory serves, could be wrong.

The reason Percy and Small survived so long is because they modernized. Steam driven hammers and such.

Anyway, it was the end, one end, of large, commercial ship building in wood. Another factor is that the large timber had been logged.

It's fitting the MMM is there now.

Sorry to ramble. Those big ships are romantic, and only romantic; beautiful but hard. They were hard building, and hard working.

[Paul Scheuer]

Wonderful pic there mmd. I'll see if I can scan the photo that I have of her in her final days. Same vessel, big change. The connection I made was that she was then owned by the Edward Hines Lumber Co. (in 1914) which is still in business here.

[Alan D. Hyde]

She has a witching good-looker of a sheer line, doesn't she Michael??? :D :D :D

Alan

[Ken Hutchins]

Wyoming, built in 1901 for $190,000, 6 mast, 390
ft long, lost March 1924 near Pollock Rip off the Massachusetts coast. I think I recall hearing she was found about a year ago.

[Andrew Craig-Bennett]

23 years is a full life for any ordinary merchant ship; she should have paid for herself very comfortably in that time and she would have been a tired old thing when she was lost.

[JeffH]

Jack, MMM will be building a full-size scuptural representation of Wyoming in frame on their grounds this year, assuming that fundraising goals are met. Judging by a model of the finished product that's in the lobby now, it'll be darned big.

Wyoming was found about a year ago, or so they think. Don't know if they've managed to conclusively identify the wreck. A list of all Percy & Small vessels and what happened to them is interesting reading. Of the 44 hulls built, only three or four managed to make it to old age. Of course, WWI took care of a lot of them...

The Phil Bolger hogged design was, I believe, an attempt to get the most lateral plane area possible in the shallowest hull possible. Rather than have a keel sticking down from the hull, the keel is straight and the hull bends up around it. Interesting, and typically Bolger-esque, idea; don't know how well it works.

Anybody on the right coast wanting an education in hog need only find the 100-year-old Victory Chimes during haul-out. When Domino's Pizza rebuilt the boat back in the 90's, the hog was built back in. I think there's well over a foot of bend...

Jeff

[Jack Heinlen]

Thanks Ken and Jeff for the additions and corrections about Wyoming.

I lived in the house there at the shipyard. There was one photo of Wyoming I remember well, her bowsprit stickin out past the house and over the road. An American football field and a third long. Really sumpthin'. I think one reason they didn't build her longer was because there wadn't no more room. :D

[Paul Scheuer]

Here's the vessel in mmd's pic above. Annie M. Peterson at age 40. http://www.imagestation.com/picture/sraid112/p4e1386d99dbf7e7c22e6781cb555ce6a/f8ff263e.jpg

http://www.imagestation.com/picture/sraid112/p923d84e7a14bf4085b9e50510a4b4ecc/f8ff263c.jpg

And a similar laker in her prime, G.J.Boyce, 136.9 x 30 x 10.3 ft, 319 tons. http://www.imagestation.com/picture/sraid112/pf1e23fcefc41c7352530dfddcc448d7c/f8ff2639.jpg

[brian.cunningham]

Great old photos

[Jack Heinlen]

An author who is worth a look about Great Lakes, NA shipping, is Walter Havighurst. The prose is a slight bit purple, but very entertaining and readable. He writes well.

[imported_Steven Bauer]

Maine's First Ship has arranged to have their replica of the Virginia built on-site at Maine Maritime Museum. Not just Maine's first, but the New World's first, also. They are fundraising now, too. I made my donation. :D

Steven

www.mainesfirstship.org (http://www.mainesfirstship.org)

[Paul Scheuer]

To try to get this back on the topic.

I've been reviewing my old photos and books to see if there's any hogging in the pics. So far I see a of of natural aging but nothing that strikes me as hogging. Maybe, as bad as some of these look, they're just too young.

The other thing I don't see is pictures of these late 1800's vessels hauled. Is it that they never were, or just not photographed.

[Andrew Craig-Bennett]

Pretty much a question of draft and tidal range, I fancy; hauling out was expensive and difficult; much easier to lay her ashore and work between tides. The Royal Navy used drydocks for its wooden warships.

[mmd]

"We don' need no steenking drydock!!"

A trading ship careened for bottom maintenance:

http://www.brownmarine.com/graphics/pph06.jpg

Captioned: "This photo was from "Bliss's Quarterly" in 1897. When drydocks were not available ships were laid on their sides by a process known as careening. The ship was wenched over and repairs made to the hull. This photo reportedy shows barnacles being scraped at a dock in Pensacola. A buildup of barnacles would slow the ship down. (Photo and information courtesy of John Appleyard taken from "Four Centuries .... a saga of Pensacola Port in action".)"

[Jack Heinlen]

The ship was wenched over I reckon more that a few ship's company were 'wenched over', never mind the careening.

Just curious, is that proper usage? smile.gif

[Andrew Craig-Bennett]

mmd - that is a wonderful photograph!

[Concordia..41]

That photo is a keeper. I think I'll save it in a new category "When ships were ships and men were men" :D

Geeze at the forces and stresses involved in careening :eek: Thanks for the good reminder that these boats withstood tremendous pressures.