Paddlewheel Science Or Lack There Of ?

Lots of good questions here, and maybe I can give my $.02 worth on some of them. Good paddlewheel design is of course, very important for any sternwheeler to handle well and be successful. Regarding the MQ, putting glass windows too low on the splashwall is not the best idea, but the MQ's splashwall was further away from the wheel than most, and probably reduced some of the debris danger. Some of those design problems could have to do with the MQ's naval architects being in the UK, and not being as familiar with western rivers, Mississippi-style steamboats (in my opinion).
The staggered bucket design on the MQ was to reduce vibration and "pulsing", and it generally does reduce those problems, better than a straight wheel.

The "Rocket City Rednecks" may hold actual Phd's in something, but I don't think their formula for determining number of buckets makes a lot of sense. The size of the flanges ("Hubs") on the wheel shaft should not be the key to the design of the whole wheel. The flanges are there to secure the base of the spokes to the shaft. The flange diameters can vary greatly between various boats (regardless of overall paddlewheel diameter), yet still serve their purpose. There are some good guidelines for paddlewheel size/construction here: paddlewheels

Taller bucket boards (i.e. deeper "dip") takes more power, but you are able to push more, so sternwheel towboats like the Barbara H have proportionally deeper dip for pushing barges -- more dip than sternwheel excursion boats of the same size. Also if you reduce the "dip" height, you can increase speed. Some of this has to do with not lifting as much water, and some of it is the buckets can "get in their own way" and have a negative affect on the flow of water up from the stern rake. Reducing the dip helps alleviate the problem (to a point).

The other problem that nearly all sternwheelers must deal with is that over time, things get added to boats, and are rarely removed. When these boats are new the wheels are sitting in the water at the optimum depth, according to design. But as stuff gets added to the boat it gets heavier, and the wheel sits deeper in the water. Deeper wheels tend to push-down and lift-up more on the water, which is inefficient.

Herring-bone wheel design does offer a small improvement in efficiency when coming ahead, but you lose some backing capability, compared to plain straight buckets. Generally the herring-bone design did not offer enough gain to be worthwhile, and it greatly complicated building them.

Well, that's all I have time for.. I'm sure others will chime in..

Input & Information !

Steve ,
Thanks so much for your input and information concerning the different aspects and thoughts concerning paddlewheel function and design !
One lingering question that I still have is , in those early days of paddlewheel design and construction did the naval architects of the day employ certain plans , designs , formulas or did they just rely on trial and error results on how well a boat and paddlewheel performed during their respective sea trials . Was there an actual science to it or was it just a hit and miss proposition and hopefully the performance of the boat would be satisfactory ? Obviously , a larger paddlewheel would be required on a larger boat , but how would the overall dimensions of the paddlewheel be calculated ? Food for thought !
Smooth Sailing !
Ted Davisson
WA-4141

Steve Huffman;28007 wrote: Lots of good questions here, and maybe I can give my $.02 worth on some of them. Good paddlewheel design is of course, very important for any sternwheeler to handle well and be successful. Regarding the MQ, putting glass windows too low on the splashwall is not the best idea, but the MQ's splashwall was further away from the wheel than most, and probably reduced some of the debris danger. Some of those design problems could have to do with the MQ's naval architects being in the UK, and not being as familiar western rivers, Mississippi-style steamboats (in my opinion).
The staggered bucket design on the MQ was to reduce vibration and "pulsing", and it generally does reduce those problems, better than a straight wheel.

The "Rocket City Rednecks" may hold actual Phd's in something, but I don't think their formula for determining number of buckets makes a lot of sense. The size of the flanges ("Hubs") on the wheel shaft should not be the key to the design of the whole wheel. The flanges are there to secure the base of the spokes to the shaft. The flange diameters can vary greatly between various boats (regardless of overall paddlewheel diameter), yet still serve their purpose. There are some good guidelines for paddlewheel size/construction here: paddlewheels

Taller bucket boards (i.e. deeper "dip") takes more power, but you are able to push more, so sternwheel towboats like the Barbara H have proportionally deeper dip for pushing barges -- more dip than sternwheel excursion boats of the same size. Also if you reduce the "dip" height, you can increase speed. Some of this has to do with not lifting as much water, and some of it is the buckets can "get in their own way" and have a negative affect on the flow of water up from the stern rake. Reducing the dip helps alleviate the problem (to a point).

The other problem that nearly all sternwheelers must deal with is that over time, things get added to boats, and are rarely removed. When these boats are new the wheels are sitting in the water at the optimum depth, according to design. But as stuff gets added to the boat it gets heavier, and the wheel sits deeper in the water. Deeper wheels tend to push-down and lift-up more on the water, which is inefficient.

Herring-bone wheel design does offer a small improvement in efficiency when coming ahead, but you lose same backing capability, compared to plain straight buckets. Generally the herring-bone design did not offer enough gain to be worthwhile, and it greatly complicated building them.

Well, that's all I have time for.. I'm sure others will chime in..

Ted, Steve is right about the theories he speaks of. In answer to your question, yes, there has been considerable "paddlewheel science" over the years. I think Alan has written about it in his Old Boat columns in the WJ, and maybe other places, too.

As far as the SPRAGUE is concerned, I would say that the marine architects and engineers of the time used all the info and empiracle knowledge they had available to them, and knew what power they wanted as far as tow size, speed, backing power, etc. They then built (I'm guessing!) the wheel to accomodate the engines and the tonnage they wanted to move. The rest of the boat was made to fit that criteria. I do know that when she first came out, the SPRAGUE had problems, and they cut down the size of her wheel in response to that. There were also some other problems that caused them to lay at Cairo for an extended period to rectify the problems. She ran relatively smoothly after that for the remainder of her career.

As far as the DELTA QUEEN and DELTA KING's wheels, yes, they were right when the boats were built, and had the correct dip. Remember those boats only drew 6 to 7 feet in California. The wheel covers were for both protection of passengers from spray and I suppose also to make things quieter. They were impractical on the Mississippi system due to drift and icing concerns. Another factor was that people did not care about "nostalgia" at the time the DELTA boats were built; they couldn't have cared less about a paddlewheel, so "wheel watching" was probably not what it might be to us today, though I'm sure some did enjoy watching/listening to the wheel.

Number of buckets: Capt. Hawley told me the more buckets, the less vibration, but there is also a point reached where power is compromised, as well. I doubt noise factored in too much.

Pitman or chain drive: I would think the weight of the wheel would determine whether the wheel could be driven by chain, but by the time diesel engines were being used to drive paddlewheels, the diesels were so small they could not be on a very big boat anyway. The reason for pitmans on a big boat was the large relatively low-pressure engines. They were mounted horizontally and built with a long stroke, and pitmans were/are the best way to transfer that power from the engine to the wheel.

All the advances in steam engine and paddlewheel design pretty much came to a halt with the advent of of more reliable and powerful diesels and the development of screw power and tunnel stern designs for towboats.

Ted
In the very early days there was a lot of experimentation. The Western Engineer built 1818 Had a single engine mounted below the main deck and the Pittman was attached to a crank in the middle of the shaft and there were two wheels set in what was a double boot jack arrangement. The builders figured she would draft 18 to 20 inches and it turned out to be 30 to 36 inches and they ended up raising the shaft. The Missouri Packet that came out in 1819 was also a bootjack the bucket arms were steel
The engine was mounted on the starboard side and there was a iron fly wheel on the port side. When I looked at the engine I felt she might have had a cutoff system for her sliding valve. I believe that the engine maybe in the Arabia Museum in Kansas City. The piping from her three boilers to the engine were copper so the pressure would have been under 60 pounds. The boilers were return flue With the smoke and heat entering the boiler through its bottom and leaving through the top of the boiler. She snagged near Boonville, Mo with a load of salt pork and flour for US Army at Fort Atkinson, Nebraska.

Carl is right about the expirimentation in the early years of steamboating. Toward the end of the paddlewheel's reign, the U.S. Engineers did a number of studies on paddlewheel efficiency, and tested some of them with a dynamometer (basically measuring how hard the boat was shoving against the device, mounted on a fixed wall. Maybe similar in concept with how tugboat "bollard pull" is measured these days). There was also the semi-famous shoving contest between the steam sternwheel towboat D.T. Lane and the steam propeller towboat James Rumsey in 1903. The Rumsey won, even though the boats were thought to be of similar horsepower, and the Lane was even given the advantage of being the upstream boat. Go to this link UW La Crosse Historic Steamboat Photographs Search: Keyword and search for D.T. Lane to see a photo of the event.

I don't know of any photos of dynamometer tests, but Alan has written on this topic in the WJ's Old Boat Column.

Thank You , One & All !

Greetings From New Orleans !
First of all , " Thank You , One & All " ! I do appreciate everyone's information and input concerning this topic that has held my interest and curiosity for all these years !

Its funny , that for all these years " In The Business " , there is still so much to be learned and understood concerning the different engineering aspects of paddlewheel design and construction !

First of all , I think that many of us simply look at a turning paddlewheel on a boat and casually think , " Well , Isn't That Nice " and then turn away and not give a second thought to the type , style , design and evolution of the paddlewheel !

Secondly , I now realize that as with any boat there is a certain degree of compromise that must be taken into account so as to reach the optimum point of efficiency !

For example , more wheel arms , less vibration BUT more weight and less speed !

So , where is that NEAR PERFECT POINT , where a well designed wheel will not only have optimum speed AND also less vibration ?

Furthermore , hopefully this information and SCIENCE will NOT be lost as so much other information and science has been but will be well preserved and just possibly be used and re-applied at some time in the future !

I for one have a whole new and enlightened appreciation for the paddlewheel and now realize many the factors and concepts that come into play with the development , design and application of an efficient stern wheel paddlewheel !

Smooth Sailing !
Ted Davisson
WA-4141

Ted Davisson;28005 wrote: Greetings From New Orleans ,
From the very first time I first laid eyes on the enormity of the paddlewheel on the Str. Sprague to the present I have often pondered the question of Paddlewheel Science Or Lack There Of !
I have this picture in my mind , of standing on the Sun Deck of the Str. Delta Queen and honestly looiking UP at the paddlewheel on the Str. Sprague when we would tie off to her when on the Yazoo River in Vicksburg !
Furthermore , was the paddlewheel designed and built around the boat or was the boat designed and built around the paddlewheel ?
Was the paddlewheel simply an afterthought and was designed and constructed to just fit on the fantail of the boat after it was designed and built regardless of other very consequential issues ?
Were there other issues at hand with the science or lack there of with paddlewheel design and construction such as ; the deep draft of the intended boat , the depth of water that the intended boat would be navigateing in , the optium speed for the indended boat and or the approximate weight of the paddlewheel that would or could have an adverse effect on the overall perfoirmance and trim of the intended boat that the paddlewheel would be afixed to ? Also , was the maintenance and care of the paddlewheel ever an issue ?
I have personally spent more hours than I care to remember in the paddlewheel of the Str. Delta Queen with sometimes an entire deck crew and consequently consumed the entire time the boat and paddlewheel was secured and which resulted in the inability for the deck crew to take care of other deck related chores !
I recall reading of the great steamboat races in which the winner of these races would be awarded the lucretive government mail contracts , so were some boats literally built for speed and consequently was the paddlewheel designed and built to increase the speed and perform more efficiently ? Is that why the herring bone wheel and the split wheel come into existance ?
To ths day I remember Captain Wagner giving the order to fill the forpeak of the Str. Delta Queen in order to act as a counter balance to help lift the stern of the boat to get the paddlewheel out of the water . In essence , he was putting the boat into an optium trim so as to create less drag and squat so as to increase the speed of the boat so as to better compete on race days and especially in the spring of the year when making good time was a major factor when going up the river to meet scheduled and profitable shore stops and the ever important date with the Belle Of Louisville !
I also remember him saying that originally when the Str. Delta Queen was constructed , her paddlewheel was designed , constructed and mounted correctly to give the DQ the proper and correct trim and propulsion but over the years with the addition of " Creature Comfort " additions , the stern and paddlewheel of the DQ literally sank deeper into the water and altered her overall trim and consequently adversely affected her overall performance !
I also remember when the paddlewheel on the late and great Str. Mississippi Queen was trimed down because it sat too deep in the water and in high water conditions with the presence of drift in the water , the MQ's paddlewheel had a propensity to literally pick up and throw drift wood into and through the windows of the the MQ's paddlewheel bar !
Was the paddlewheel also designed and constructed to accomodate another function such as its overall noise factor ? I have herd that the greater number of wheel arms on a paddlewheel would lessen the noise factor from splashes that the wheel would make when slapping through the water . Also , originally on both the Str's Delta King and Delta Queen , there was a paddlewheel box constructed over the paddlewheels to dampen the noise so that the on board passengers could rest better at night . Having said that , I always enjoyed the sound and view of the paddlewheel splashing through the water and was just part of the overall steamboat experience !
Also , recently on the National Geographic program , " Rocket City Red Necks " , it was mentioned that the formula for constructing a paddlewheel was to take the diameter of the inner flange of the wheel and multiply it by 2and that would five you the required number of wheel arms . For example , if the diameter of the inner flange was six feet , you would multiply that number by 2 , so the minium required number of wheel arms would be 12 . Now haivng said that , I am sure ther there are other factors and issues that must be taken into account to make that determination as well !
One other question of the Science Of The paddlewheel Or Lack There Of , was it ever an issue with the design and construction of the paddlewheel , if the wheel was to be operated by pittman arms or by a chain ? If it was to be operated by a chain , would the overall weight of the paddlewheel be an issue if it were to be chain driven ?
I also remember sitting in the Pilothouse of the Str. Delta Queen and just listening for hours on end to the Pilots like Louden , Ware , Tate , Zimmer , Karnath , Hamilton , Winford and Mac Arthur and others address this subject and give their time hardened experience on how a good paddlewheel should be constructed ! I remember that these same Pilots would mention what they refered to as a " Square " paddlewheel that was of the same diminsion of width and heighth and was generally the best design and would give the best overall performance . I also wondered why these same " Masters Of The Mississippi " were NOT consulted when the MQ 's wheel was designed and constructed and then had to be re-designed and re-engineer by the so called experts of the day ! Go Figure !
So , hopefully some one with a better insight or knowledge of this issue will chime in and enlighten us all to the factors that came into play with the science and design of the paddlewheel !
Smooth Sailing !
Ted Davisson
WA-4141

*RE: DQ wheel/Mail Contracts*

Hi, Ted & all who responded above:
First, I'm no expert in any field with limited technical knowledge [101 in power mower, paint brush training] possessed by others on this board in the 'know' from their experience. The 'wheel housings' on the DK/DQ have been mentioned in the past on this site. Built of wood with copper linings, the housings also kept spray from blowing back on the stern decks while underway in vast, windy San Franciso Bay along with 'dampening' the sound as both boats were constructed for the 'night boat' trade. The housing [Among other things] on the DQ irked Capt. Tom Greene and he had all removed to fit the lines/tradition on the rivers here. I can only imagine what all that copper would bring on the salvage market today.

People often forget the DK/DQ then operated between two marine environments: salt water in the bay, fresh water on the Sacramento. John Burns, old Jim's son, related to me here that in his time there was also a large fresh water tank on the boat to feed the boilers while docked in San Francisco. John said water was sucked up often with large fish being pulled in coming down the Sacramento, which they could see taking off the tank housing. Prolonged dockage in San Francisco [As happened during the long maritime strike in the 1930s] had old Jim concerned due to barnacles forming on the hull. Jim wanted the KING out of the bay and up the Sacramento to prevent this. The story gets fascinating and was told to me, along with Stan Garvey recording in his book, how Jim, Capt. King, younger John sneaked aboard past the picket lines acting coy and innocent to raise steam and take the boat up river with just a few crew members. John slipped over from the pier, darting in through the pitman openings. All went well until the intake pipe became clogged from being docked so long at the SF company pier. Water levels in the indicators fell to nearly -0- with John, serving as a licensed fireman, quickly pulling the fires to prevent a disaster. "I nearly died seeing the low water in the glass gages," John reported. The boat stopped, drifted, grounded on Alcatraz prison island on the gravel. John, an athlete, jumped over the side to clear the pipe with prison guards on the ramparts with guns and bull horn yelling, "Get back on the ship!...get back on the ship!" Water levels were restored with them steaming on. John said if the maritime strikers had headed them off at the pier they could have had a "bad way to go."

Steamboats/steamships earning U.S. Mail contracts of the day was, indeed, based on speed with contracts being clear on mail delivery schedules. The contract was on a kind of 'sliding scale' as per speed of the vessels. It was a coveted, lucrative contract but not without problems. Some higher speed boats/ships naturally burned more fuel in either coal or oil to meet the schedule with, in turn, reducted financial realities in the contract--not figured by Washington, D.C. postal officials. A tricky business along with the usual cargo and passenger loads and schedules to contend with.

Right you are about increased "creature comforts" deepening the boat's draft with the wheel buried deeper. John said, "Dad and DENNY BROS., Dumbarton, Scotland, projected the draft on the boats as close as possible: freight, vehicles, passengers, fuel etc." Construction of big ocean cruise ships today even figure in the weight of all that paint applied inside and out. *Not to repeat a previous posting, but how many 'older timers' here remember seeing the freight load lines incised on the teakwood deck of the DQ's dining room? Was there for years, but I have no idea if it was sanded out or filled in with wood patch filler. Observers long noted the DQ's wheel rolling around on the stroke with a very slight 'pause' at the top of the cylinder run. Well, what do I know?

R. Dale Flick
Coal Haven Landing, Ohio River, Cincinnati.

Ted: Way quotes James Rees & Sons in part that the wheel would be three strokes (of the piston) in diameter, have ten arms for 14' diameter wheels ranging to 18 for a 30' wheel. The Pitmans (length) C to C would be 4-1/2 to 5 strokes;p packets 3-3/4 strokes or more...the most efficient paddlewheel has no more than three buckets immersed; one fully and two partially. No mention is made of bucket depth or length. The rest of the chart can be found in S&D of June of 91 according to my notes. Cap'n Walnut.

Tom , Thanks So Much For That Information !

Tom ,

Thanks so much for that information ! I always assumed that there was some type of formula or " Rule Of Thumb " for the design and mounting of a paddlewheel !

One quick and final question concerning this topic . I know from experience that the engines and screws not only on tow boats , tug boats and yes even ships , do NOT turn up as much in the Astern position as they Do in the Ahead position . So , my question is ; on the old steamboats with paddle wheels and regardless if they were sternwheelers or side wheelers , were the engineers on those boats able to get as many revolutions in the Full Astern position as they could in the Full Ahead position ?

I was always told that on the modern day diesel boats the reason for the fewer revolutions in the Astern position was due to the design of the propeller which was designed to be more efficient in the Ahead position and not the Astern position .

So , was the paddlewheel on a steamboat able to function as efficiently in the Astern position as it could in the Ahead position ? Furthermore , was it an issue with the design and type of the respective steam engine or was it an issue with the design and type of the paddlewheel for it to turn up as much in the Astern position as in the Ahead position ?

Smooth Sailing !
Ted Davisson
WA-4141

Tom Schiffer;28024 wrote: Ted: Way quotes James Rees & Sons in part that the wheel would be three strokes (of the piston) in diameter, have ten arms for 14' diameter wheels ranging to 18 for a 30' wheel. The Pitmans (length) C to C would be 4-1/2 to 5 strokes;p packets 3-3/4 strokes or more...the most efficient paddlewheel has no more than three buckets immersed; one fully and two partially. No mention is made of bucket depth or length. The rest of the chart can be found in S&D of June of 91 according to my notes. Cap'n Walnut.

Bob , Interesting Point About The DQ & DK's................

Greetings From New Orleans !
Bob , interesting point about the DQ & DK's paddlewheel's design and correct " Dip " in the water .
However , and I am just wondering if any one has taken this into account , the fact that those two boats were designed and constructed to operate in both salt and brackish waters ! Consequently , the two steamers were in all likelihood designed to float higher in the salt and brackish and buoyant Pacific waters of California . So , when the Str. Delta Queen was towed over to the fresh waters of the Mississippi and Ohio rivers , she naturally sank lower into the fresh and less buoyant waters of the inland rivers !

So , by just bring the DQ to the Mississippi River system she naturally sank deeper into the river and altered her original designed deep draft marks . Now , no telling how much she naturally sank into the fresh river water but even a few feet would be substantial enough to change the paddle wheels profile and efficiency !

Food for thought !

Smooth Sailing !
Ted Davisson
WA-4141

Bob Reynolds;28014 wrote: Ted, Steve is right about the theories he speaks of. In answer to your question, yes, there has been considerable "paddlewheel science" over the years. I think Alan has written about it in his Old Boat columns in the WJ, and maybe other places, too.

As far as the SPRAGUE is concerned, I would say that the marine architects and engineers of the time used all the info and empiracle knowledge they had available to them, and knew what power they wanted as far as tow size, speed, backing power, etc. They then built (I'm guessing!) the wheel to accomodate the engines and the tonnage they wanted to move. The rest of the boat was made to fit that criteria. I do know that when she first came out, the SPRAGUE had problems, and they cut down the size of her wheel in response to that. There were also some other problems that caused them to lay at Cairo for an extended period to rectify the problems. She ran relatively smoothly after that for the remainder of her career.

As far as the DELTA QUEEN and DELTA KING's wheels, yes, they were right when the boats were built, and had the correct dip. Remember those boats only drew 6 to 7 feet in California. The wheel covers were for both protection of passengers from spray and I suppose also to make things quieter. They were impractical on the Mississippi system due to drift and icing concerns. Another factor was that people did not care about "nostalgia" at the time the DELTA boats were built; they couldn't have cared less about a paddlewheel, so "wheel watching" was probably not what it might be to us today, though I'm sure some did enjoy watching/listening to the wheel.

Number of buckets: Capt. Hawley told me the more buckets, the less vibration, but there is also a point reached where power is compromised, as well. I doubt noise factored in too much.

Pitman or chain drive: I would think the weight of the wheel would determine whether the wheel could be driven by chain, but by the time diesel engines were being used to drive paddlewheels, the diesels were so small they could not be on a very big boat anyway. The reason for pitmans on a big boat was the large relatively low-pressure engines. They were mounted horizontally and built with a long stroke, and pitmans were/are the best way to transfer that power from the engine to the wheel.

All the advances in steam engine and paddlewheel design pretty much came to a halt with the advent of of more reliable and powerful diesels and the development of screw power and tunnel stern designs for towboats.

I can only say from experience that diesel-electric sternwheelers, and direct-reversing diesel sternwheelers can turn the wheel as fast when backing as when coming ahead (if that's what you mean?). I can't speak for steam, but my guess would be there is no difference in through-put with the throttle valve open, whether the engines are shipped-up in reverse, or ahead. I'll leave that to those who know!

The hull of a sternwheeler needs a good stern rake in order to let the water go under the boat without restriction when backing. Otherwise the water will pile-up at the transom and the boat will be a "bad backer". A paddlewheel with straight buckets will do the same work when backing as when coming ahead. (unlike propellers blades, which by design are less efficient when backing).

Ted, when loading barges in salt water, we were always told to load 6 inches light if we were going to deliver in fresh water. I have noticed about the same thing in more recent years, that if we load in fresh water (St. Louis) for delivery to a Gulf coast port (say, Panama City, FL), that the 6 inch rule is pretty good. I know it is not perfect, especially when you get to deeper drafts and larger volumes, hence the Plimsoll marks you see and use on ships.

So, in answer to your question about the DQ drawing considerably more water on the Mississippi than she did in SF Bay, I don't think it would really be any significant difference. I think also that the water in Sacramento is pure fresh water, though I don't know this for sure.

Fresh Water Allowance

Greetings From New Orleans ,

Bob , thanks for your thoughts and input on this topic but there is another issue that comes into play here as well .

Its my understanding there is anoyther factor that is refered to as a vessel's Fresh Water Allowance and is the varible that comes into play when any vessel makes a transit to or from fresh water and salt water .

Today , for example I am on a ship that has a Fresh Water Allowance of 213 mm and when calculated to feet and inches , it comes to just over eight inches lower in the water when the same vessel is in a fresh water environment .

When the Str.'s Delta Queen and Delta king were working in the San Francisco to Sacromento trade no telling where the salt water finished and where the fresh water began . Another issue that effected the location of the fresh and salt water was the amount of fresh water that was coming out of the heaqdwaters of the Sacromento River . When the Mississippi River is at a dead low condition for any length of time , I know that New Orleans and all the lower towns and communities that line the river experience what is referred to as salt water intrusion . This salt water intrusion that literally comes up the river contaminates the water supplies of these same towns and communities to such an extent that many times fresh water has to be literally trucked down to these sames towns and communities .

My point is to all this is that even if the paddlewheels on these two steamboats only sinks an additional six to eight inches , these same paddlewheels would in all likelyhood loose a certain degree of efficiency , speed and ultimately control .

It has also been brought to my attention that the Plimsol Lines that are present on the mid ship section of a ship or sea going barge are there to mark the seasonal load lines that a vessel may be loaded down to .

Smooth Sailing !
Ted Davisson
WA-4141

Bob Reynolds;28050 wrote: Ted, when loading barges in salt water, we were always told to load 6 inches light if we were going to deliver in fresh water. I have noticed about the same thing in more recent years, that if we load in fresh water (St. Louis) for delivery to a Gulf coast port (say, Panama City, FL), that the 6 inch rule is pretty good. I know it is not perfect, especially when you get to deeper drafts and larger volumes, hence the Plimsoll marks you see and use on ships.

So, in answer to your question about the DQ drawing considerably more water on the Mississippi than she did in SF Bay, I don't thiNEnk it would really be any significant difference. I think also that the water in Sacramento is pure fresh water, though I don't know this for sure.