# Tonnage Hatch/Dunnage or Tonnage - merged threads



## ccurtis1

I recall many moons ago, on I think a Palm Line vessel, there was a small hatch towards the stern referred to as the "tonnage hatch". I do not recall it being used for cargo (although I may be mistaken), it seemed to be a storage compartment for ropes etc. What was the significance of the "tonnage hatch"?. Was it to do with reserve buoyancy? I only came across this feature rarely on the ships I sailed upon.


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## Geoff Gower

My understanding of a tonnage hatch was a small secure under-deck space in which were stowed items of considerable value. Hatch covers and tarpaulins were supplemented with steel locking bars and padlocked in place.


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## Pat Kennedy

This is an excerpt from shipinspection.eu mariner's handbook.

_The traditionally designed general cargo vessels of the 1950s and 1960s (still found in some old fashioned trading areas today) was the “three-island type” with raised forecastle, accommodation block and raised “poop” ._

_The spaces on deck between these structures were exempted from tonnage measurement but could be used for cargo. Owners did carry cargo in these “wells” and protected it by awnings and other shelters which gradually became more permanent. Eventually the spaces were totally enclosed with a permanent deck above. These spaces became known as the “shelter deck spaces_

_However, to maintain the fiction that the space above the original upper deck was still “open”, the shelter deck spaces were interconnected by openings and a small “tonnage hatch” at the after end of the ship led to the shelter deck space._

_The tonnage hatch could not be permanently or substantially covered. This led to a concern for the safety of these vessels. For example, if there was fire or flooding, the danger could spread from one end of the ship to the other without hindrance. The tonnage mark was introduced to encourage shipowners to close all these “tonnage openings” and restore the vessel’s integrity without being penalised by having the shelter deck space included in the vessel’s tonnage. This method was not popular with port and other authorities which derive their revenue based on the ship’s tonnage._


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## Mike S

I served my time on Durham which was an example of this system. Worked well although it is true that there was a whole upper deck that was referred to as the shelter deck and it also meant that we had to chock the hatch covers in the shelter deck too to seal off the hatches. Cadet ships had plenty of free labour. (Thumb)(Thumb)


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## stan mayes

Hello Colin,
About six of the Palm Line ships had Tonnage hatches but I don't know for what specific reason.
The aft mooring ropes were always stowed there at sea.There was a hatch opening with 6 feet long hatchboards to cover it.From the space below there was an opening which allowed entry to a cargo space aft with a bulkhead separating it from the steering gear area...Outward that was usually full of second hand furniture and fridges which the African crews had bought..
As soon as the dockers finished work in the evening a few vans would arrive alongside the ship with the furniture the crews had bought from local dealers.
Homeward there was usually many bales of rubber in that space and I believe the dockers were paid extra for discharging it.
Some of Elder Dempster and Guinea Gulf ships also had Tonnage hatches.
Regards,
Stan


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## fred henderson

Gross (GRT) and Net Tonnage (NRT) had nothing to do with the weight of a ship but were certified measurements of the enclosed watertight volume of a vessel, with 100 cubic feet being equal to 1 ton. Harbour dues and other charges were levied on the certified tonnage. As a cost saving measure, owners of tween-deck vessels incorporated a small tonnage hatch abaft the main hatch of the aftermost hold. When the ship was surveyed this tonnage hatch was not watertight, so that the volume of the entire tween-deck of its hold was not watertight and excluded from the tonnage certificate. The measures a prudent captain applied to this hatch after sailing where between him and his crew. (Gleam)


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## Alistair Macnab

*Tonnage Hatch - Shelter Deck Ships.....*

The tonnage hatch was a feature on many Bank Boats. As described, it was a small hatch abaft the aftermost hatch which was the full width of the upper deck hatches but was only one hatchboard wide in a fore-and-aft direction (about 4.5 feet). It had no cleats or battens to secure it. The flanged plate coaming was less that 1.0 ft. high and tarpaulins which were covering the hatch were held down by wires and bottlescrews. There were, however, centre handles on the underside of each hatchboard which would accept wire and/or rope securing as additional lashing down to securing points below.

The purpose of this tonnage hatch was to exempt the entire upper tween deck from the ship's gross and net tonnage measurement. This was obtained by the fiction that the tonnage hatch created an "opening" into the upper tween deck all the way forward to the collision bulkhead so that the upper tweendeck was technically an open although "sheltered" deck space. Hence the term a "Shelter Deck ship".

In this "open" tweendeck space, any intervening transverse bulkheads did not have to be to scantling and had "tonnage openings" in them consisting of "storm boards in channels to obtain access from one tween deck to the next through these openings.

As time went on, the original open shelter deck was subdivided by 'fire" bulkheads with the same tonnage openings, and access fore and aft was obtainable past the engine room casing by passage ways with aforesaid storm boards at both ends.

Hatch flange plate coamings in the shelter deck were fitted with battens and cleats for securing but unlike the hatch coamings above them on the weather deck, these coamings were less than 12" high enough to secure a tarpaulin as, of course, this was really the "upper deck" of a shelter deck vessel, the actual weather deck above being only for the "shelter" of the shelter deck below.

All this meant that a shelter deck ship had a gross and a net tonnage that excluded the entire measurement of the shelter deck space - very convenient for port, pilotage and canal charges that were based on these official tonnages.

As time went on, the tonnage mark system of ship measurement came into force. This was a triangle, apex down at the Plimsoll position that stood on two lines representing the maximum loading in the open shelterdeck condition and the closed shelterdeck condition. A ship was deemed to go from one condition to the other as she became lower in the water thus a high stowage factor cargo would retain the shelterdeck gross and net and a low SF would entail the application of the higher gross and net.

Those organisations that assigned charges to gross or net ships tonnage found themselves losing out revenue-wise and very quickly altered their tariffs to reflect that dual tonnage ships would be assessed at the higher official tonnage in future. This negated the benefit of the shelterdeck and dual tonnage benefit to owners and the system went out of practice.

The dates are as follow:

"Fleetbank" (built 1953 by Harland's Belfast) Open Shelterdecker

"Laganbank" (built 1955 by Harland's Belfast) Additional "fire" transverse bulkheads installed in Calcutta in in 1956 but still an Open Shelterdecker.

"Carronbank" (built by Harland's in 1957) as an Open Shelterdecker but converted to an open/closed Shelterdecker in 1959 by the assignment of a tonnage mark.

All subsequent ships of the class were assigned a tonnage mark and when a new larger class was delivered ("Taybank" in 1963) the dual tonnage had disappeared altogether.

Below the shelter deck in these ships, additional orlop decks, lockers, reefer chambers, and deeptanks could be fitted as customary and these were included in the gross and net tonnages as normal.

Stowage of cargo was, of course, permissible in the shelter deck and often, the tonnage hatch space was used for odds and ends like mooring ropes and the aft insurance wire reel or perhaps B.A. fenders. It was sometimes even used for cargo if some form of separation from all the other cargo was warranted. I understand that in pre-war shelterdeckers, the tonnage hatch space was often used for the gunners' quarters as the shelter deck concept was abandoned during WW11.

Does this answer the shelter deck questions?


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## Duncan112

Thanks Alistair, but looking at my discharge book the "Fish Class" were dual tonnage - Troutbank being 12213.89 GT 7729.77 NT submerged and 8243.22 GT 4640.78 NT not submerged, with as you say an inverted triangle. I can't remember any tonnage hatch on these ships so how did that system work?


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## Erimus

In 1958/1959 I was working on the Tees and we had the Takoradi Palm in port and this small hatch was stowed with tea chests containing passports being sent out by Crown Agents.

geoff


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## Derek Roger

Some Brocklebank ships has this feature ; Open or closed shelter deck . Main issue was that with the open shelter deck the Suez canal dues were less . All to do with fees . Derek


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## Alistair Macnab

*Dual Tonnage*



Duncan112 said:


> Thanks Alistair, but looking at my discharge book the "Fish Class" were dual tonnage - Troutbank being 12213.89 GT 7729.77 NT submerged and 8243.22 GT 4640.78 NT not submerged, with as you say an inverted triangle. I can't remember any tonnage hatch on these ships so how did that system work?


Well, I'm jiggered! As far as I can tell, there's no purpose in dual tonnage these days but your information is very interesting and keeps the topic alive!
Alistair


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## Cisco

What was often called the upper tween deck on shelter deckers was in fact the main deck and what many called the main deck was in fact the shelter deck..ie the top deck if you want to get really technical....

Shelter deckers also had 'tonnage alleyways' that ran down either side of the accomodation at main deck level. On the shelter deckers I was on the port side one was accesed via the fridge room space while the one on the starboard side was effectively just dead space.
The tonnage rules also led to there being no real doors to the focsle... just frames that you dropped wooden boards down into.


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## ccurtis1

Thank you very much guys for the input. I am/was an engineer, but this tonnage hatch thing always fascinated me.


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## NoR

The tonnage system was/is ridiculous, causing ships to be built in a way that contributes nothing to their seaworthiness or viability, purely to mitigate against some some daft tax raising legislation.


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## IRW

I can't remember which Bank Boat I was on but we went from open to closed shelter deck. The wooden battens in the tween decks were replaced by steel plates which were stored beside these doors all the way from ford to aft incl the alleyways each side of ER spaces. The wooden hatch boards on tonnage hatch were replaced with a single steel hatch which had lugs to make a W/T fit. Then we were over the side to change the load line marks. As far as I remember it was used for heavy/light cargoes i.e. heavy ores/ lighter grains. IRW


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## Duncan112

Scanned the stamp in my discharge book in and here we are, there are a couple of members on the site that stood by the "Fish Class" they may have an idea?


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## kypros

Just to throw another version into the discussion concerning the small hatch aft of number five hatch,I sailed on a few vessels with this layout and recall these small hatches refered to as the lazarette or lazarite could be wrong on the spelling but as Erimus states they where sometimes used for high value cargos,spirits,cigs and other expensive items and banknotes etc.they were usually wooden hatchboards about five or six feet width only going down to the tween deck but cut off from the rest of five hatch by steel bulkheads,also as extra security I have seen the hatchboard tiebars temporary welded on these hatches does any other members recall the name I refered to.KYPROS


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## China hand

Just checked my books, and DACEBANK was the same. I stood by building the bloody thing and I still can't remember a tonnage hatch.
On the India~South America trades it was quite usual to open/close two or three times a trip. Open to Bs.As with general, closed to elsewhere with grain, open again for whatever. In those days I only undid the bolts in the tweendeck access doors and have no idea what paperwork the Old Man went through. I was never master in a dual tonnage vessel.(Read)


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## Michael Taylor

On numerous trips from India to the UK with Ellermans we used the tonnage hatch for raw skins to avoid contamination.


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## Cisco

I've been scouring the Gallery to find some GA plans... odd that I can only find 2 shelter deckers...
http://www.shipsnostalgia.com/galle...k-2c-squeze-2c-bang26amp-3b-blow-ship/cat/510
http://www.shipsnostalgia.com/gallery/showfull.php?photo=32421


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## NoR

MacAndrews small V class (Villegas Vives etc) had a tonnage hatch right aft.


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## Geoff Gower

*Use of a tonnage hatch*



kypros said:


> Just to throw another version into the discussion concerning the small hatch aft of number five hatch,I sailed on a few vessels with this layout and recall these small hatches refered to as the lazarette or lazarite could be wrong on the spelling but as Erimus states they where sometimes used for high value cargos,spirits,cigs and other expensive items and banknotes etc.they were usually wooden hatchboards about five or six feet width only going down to the tween deck but cut off from the rest of five hatch by steel bulkheads,also as extra security I have seen the hatchboard tiebars temporary welded on these hatches does any other members recall the name I refered to.KYPROS


I said earlier that the tramp ship's I sailed on 1954-1959 ( m/s Lambert bros ltd) always used the tonnage hatch for special high value cargo as mentioned here-- Geoff


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## Derek Roger

From my discharge book when signing off I find the following .
Mahout 1966 show as a closed shelter deck / Net Tons 5198.6 Gross 9213,77

Mahout 1968 show as as having an open shelter deck Net Tons 3397.13 Gross as 6867.1 
Quite a difference and worth the effort in fees I would presume .

Markhor ( sister ship ) 1969 show as at the time she had her shelter deck open .
Net tons 3397 Gross 6867.4 
Net Tons 
As I recollect Mahout had steel covers ; not wooden battons . Cheers Derek


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## joebuckham

the tonnage hatch was one of the regulations that allowed the shipowner to have the deck between the tonnage deck and the shelter deck exempted from cargo dues .the coamings were supposed to be no more than 12 " high with no cleats for battening down, also no stanchions so close that they could be used for same, and definitely no tarps . there was to be access for'd (secured by temporary plates in the hold bulkhead) and aft (through water tight doors if crew accommodation was adjacent. approved scuppers and washports to be fitted. it was to be sited not more than one twentieth of the ships length from the after side of the sternpost side, and four foot in length and as wide as the adjacent cargo hatch.
special cargoes on the ships I was on were carried in lockers purpose built for the voyage but I have a line drawing of a prince boat showing a special cargo locker just abaft the tonnage hatch


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## bobs

Tonnage openings or hatches were rendered obsolete in 1965 by the Tonnage Mark Scheme, which permitted the exemption of shelterdeck spaces to be based on a reduction of draft instead of having these openings, provided the change was ratified by the government concerned


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## Derek Roger

bobs said:


> Tonnage openings or hatches were rendered obsolete in 1965 by the Tonnage Mark Scheme, which permitted the exemption of shelterdeck spaces to be based on a reduction of draft instead of having these openings, provided the change was ratified by the government concerned


Hi Bobs ; My post 23 shows them in use 1966 through !969 .


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## bobs

Derek: The Tonnage Mark Scheme didn't outlaw tonnage hatches right away, just made them unnecessary in future. I don't know when the UK ratified the 1965 agreement but it was quite likely some years after the plans for your ships had been drawn-up.
Bob


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## Samsette

*Dunnage or Tonnage*

I sometimes see the the word Dunnage Hatch/Hold used, to describe the small, aftermost hold on some ships. I was of the opinion that its proper name is Tonnage Hatch. It is known as that on American ships so, would it not be universal?


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## Barrie Youde

This takes me back to childhood days in the early 1950s, when I was given an ordinary pencil which had been given to a shipmaster friend of my parents. He had just returned from a trip to New York where (as I learned later) the stevedore (from the firm of Quinn) had given him the pencil. Emblazoned down the side of the pencil was the advertising slogan "Quinn Dunnage For Better Tonnage".

I never forgot the slogan - but it was only later that I learned what it meant!


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## Erimus

Interesting thought...there isn't much one can say....if anyone historically had said Dunnage Hold to me I would have always thought of the small hold, in those days,of mine, dunnage was often carried by ships and reloaded after discharge. These days much of the timber is supplied new and certified each trip and is landed for destroying at destination.....certainly this was the case on the last ships I acted as Cargo Super for...Canada.,Australia & China.

geoff


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## China hand

Tonnage hatch was the non permanent closing hatch used to ensure that an open shelter deck ship was indeed open. In fact it was just as secure as any other hatch.


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## Pat Kennedy

It was always called the tonnage hatch. I never heard of a dunnage hatch.

See this thread for further information;

http://www.shipsnostalgia.com/showthread.php?t=54761


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## Chris Isaac

It was called a tonnage hatch but was often used to stow unused dunnage.
Dunnage was preserved as it was very useful negotiable currency on the Brazilian coast. 
Bars of soap, dunnage and cartons of Chesterfield...... happy days for cadets!


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## Samsette

Thanks for that link, Pat. I should have done a search, and saved opening another thread on the same subject.

Kypros jogged my memory of the old T.S.S. Nestor (1913) with his mention of the Lazarette. That is what it was known as aboard that old lady.


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## spongebob

When there was a craze for wood turning on the ship's engine room Colchester lathe we used to haunt the quaysides looking through piles of dunnage.
It was surprising what we found , anything from eucalyptus hardwoods through to softwoods of all sorts. I recall scavenging around the Adelaide docks at night and coming up with some lengths of about 3 x 3 Mahogany that may not have been dunnage but it made beautiful tapered stool and table legs.

Bob


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## Leratty

dunnage hatch when I was on ships that had them were small hatches aft, kinda like a attic where all sorts of things were stored by the bosun-lampy. I recall having a hatch board sent (dropped) down & hitting me in the back just above the waste when down there stowing this & that. I & the bosun thought I would be paralysed as could not get up or walk everything numb they had to sling me up on deck then carry me to my cabin. Thankfully I was able to get around the next day. Feel that is the cause of my back problems every now & then now?


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## tsell

B\)


Samsette said:


> Thanks for that link, Pat. I should have done a search, and saved opening another thread on the same subject.
> 
> Kypros jogged my memory of the old T.S.S. Nestor (1913) with his mention of the Lazarette. That is what it was known as aboard that old lady.


On one ship in the early 50's we had a Lazarette, it was used by the lampie to store his stuff, as well as the cook where his spuds and other vegies were stored. 
It was also the place where Freddie, our former POW second steward, kept his still and fermenting potato peelings - and whatever else went into it. 
He obviously had the collusion of cookie - who was always pissed - and of lampie - who was often half-pissed!
Mixed with Lauchlin Rose's ship's lime juice and sugar, it wasn't a bad drop either! The barter system provided Freddie, who was a chain smoker, with a constant supply of ****.

Taff


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## 8575

Duncan112 said:


> Thanks Alistair, but looking at my discharge book the "Fish Class" were dual tonnage - Troutbank being 12213.89 GT 7729.77 NT submerged and 8243.22 GT 4640.78 NT not submerged, with as you say an inverted triangle. I can't remember any tonnage hatch on these ships so how did that system work?


I sailed on Trout and Rudd as Mate and never gave a thought to the dual tonnage in the sense that there was no Tonnage Hatch. I can't even remember if they had the watertight openings in the TDs, probably because they were never open - out of sight out of mind!

As a cadet in Ben Line I sailed on the Benvannoch (built late 1940s) and she had a Tonnage Hatch that we occasionally used as an overflow for bales or cartons/crates. The hatch had a centre beam and wooden hatch boards and tarps. The master (Eddie Kinnaird; a good skipper for cadets) used to do the then version of weight training by standing under the hatch beam and lifting it up and down on his own! No-one else tried to emulate him.


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## 8575

Reading again through Alisatair's explanation of tonnage etc. makes me think that it is the best bit of writing on tonnage that I've read; certainly far better than some of the stuff I was told or read at college many moons ago. Thanks Alistair for some clarity.


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## China hand

Wasn't the tonnage opening at the after end of the crew alleyway in the fish class Bank boats? Seem to remember something about that. Maybe wrong.


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## Duncan112

Can't remember, thought the crew bathroom was there, but IIRC one of the causes of Global Mariner (ex Ruddbank) foundering so fast was doors between the holds being left open causing faster longitudinal flooding. I always assumed these were fitted to improve the use of exhibition space at the conversion but perhaps they were an original feature.


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## randcmackenzie

The tonnage hatch was not necessarily aft of No. 5 (or the aft hatch).

I was on one ship (Scotstoun of 1965) where it was at the forward end of No.2.

She was trading as a closed shelter decker so the hatch lid was bolted and watertight.

The fiction being maintained with an open shelter deck was that the tonnage hatch was not weathertight, hence no batten bars or wedges, the tarpaulins were lashed down one way or another.


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## dave kirkham

Hi Guys,
We had tonnage hatch on all the Hain's ships I sailed on, these were standard 5 hatch tramps and the tonnage hatch was always abaft of No 5.
On Treneglos etc, where main hatches were Mcgreggor single pull, I seem to recall the tonnage hatch had a steel plate cover, bolted down with a rubber gasket watertight seal, and access 'booby hatch'.
I still have some old cargo plans which shows us using the tonnage hatch for speci cargo, like cases of photo film on Japan-Brazil run.
I can also remember loading corned beef in tonnage hatch on return run.
Whether this was strictly legal or not I am not sure?
Interestingly I have cargo plan for Trewidden on UK-NZ run showing tonnage hatch empty. But even then way back in the 1970's Kiwi dockers were reknown for strict adherence to health & safety.
We used to do various things on cross trades, which we wouldn't do when running in or out of UK or New Zealand. 

dave


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## alan ward

The Owerri definately had one,it was where the crew stowed their various bits of furniture


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## Enri

#26 bobs, I sailed on the Benledi in the mid 70's which I'm sure had two load lines, and was also taught about the different tonnages for second mates and mates, both studied for in the 70's, so am surprised you note that were rendered obsolete in 65.


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## dave kirkham

Hi Guys,
I am not sure of my facts, my memory isn't as good as it once was, but did this open/closed shelterdeck differentiation persist in transit fees for the Panama and Suez canals? that would explain why we sometimes used them as cargo space, but left them clear when transiting the canals?

Dave


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