Gross tonnage - 22 Cruiser

C

Ctarmigan

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C Dory Year
2004
C Dory Model
22 Cruiser
Hull Identification Number
CD022102J304
Vessel Name
Ptarmigan
Hello all,

This is my transition from wannabe to something like a brat - my 2004 22 Cruiser was dropped off last week, and I'm happily puttering away at it in prep for hitting the water. Thanks, all, for being such a knowledgeable and pleasant crew - I don't know if I would have bought the boat without you.

On to business: I'm applying to modify the info associated with the boat's MMSI - a change from the previous owner's info to mine. The application is straightforward, but for one detail - it requires the vessel's gross tonnage.

My searches here and elsewhere haven't uncovered it, but I'm sure the knowledge exists here. What's the gross tonnage of a 22 Cruiser? I gather from discussions of vessel documentation it's >5 tons, but I'd rather be more specific if I can.

Cheers,

Ctarmigan
 
Ctarmigan,
I got 2.64 tons using what I remember of the Coast Guard formula of gunwale height 3’ x width 8’ x 1/2 boat length of 22’ /100 = 2.64 tons. Manufacturers specs may different.
Roger
 
I have documented a 22, with a calculated Net Tonnage of 5.13 tons. Using the formula and measurement on Document: CG-5397. The deck house of the C Dory is a significant figure. I get the hull at 3.87 and the deck house at 1.26. The hull "K" is 1, the Hull "S" factor is .67 (although that is conservative because of the boxy shape of the hull.
 
thataway":1z7kbtg2 said:
I have documented a 22, with a calculated Net Tonnage of 5.13 tons. Using the formula and measurement on Document: CG-5397. The deck house of the C Dory is a significant figure. I get the hull at 3.87 and the deck house at 1.26. The hull "K" is 1, the Hull "S" factor is .67 (although that is conservative because of the boxy shape of the hull.
Click to expand...

If the deckhouse structure volume doesn't exceed the hull volume, it doesn't count (at least in the simplified measurement for the gross tonnage calculation). Further, the calculated gross tonnage is truncated. So, using the info you provided in your post, your documented 22 has a GRT of 3, and is not eligible for documentation....?

REF: http://qualitymaritimetraining.com/wp-c ... fied_0.pdf
 
Missynme":3af3lpxi said:
Ctarmigan,
I got 2.64 tons using what I remember of the Coast Guard formula of gunwale height 3’ x width 8’ x 1/2 boat length of 22’ /100 = 2.64 tons. Manufacturers specs may different.
Roger
Click to expand...

That quick formula works for most sailing hulls. For most powerboats, a similar formula would be [height X width X 0.67 X length / 100 = GRT].

Using your rough dimensions, that would calculate to 3 x 8 x 0.67 x 22 /100 = 3.54 tons. That's pretty close to what Bob calculated for the hull of his 22, likely using more precise measurements.

Either way, they would both be truncated to 3 tons for reporting purposes.
 
Whew - a bunch of different answers. I knew there was a reason I couldn't search up a straightforward number.

I wasn't looking forward to choosing who I thought was correct. Turns out, though, I don't have to, because for very bureaucratic reasons no one is.

This is on me - I wasn't explicit about being in Canada. AK Angler's link to the Coast Guard Tonnage Guide had me thinking there must be a Canadian equivalent. I dug around, and turns out there is, and the Gross Tonnage calculations are different (of course they are...).

For posterity, here's what I found.

Transport Canada provides three Gross Tonnage calculation options.
a) Assigned Formal Tonnage - linked to vessel length, where all vessels <8.5m are assigned Gross Tonnage of 4.99
b) Simplified Tonnage Measurement - calculated using length, breadth and depth (in m), with the formula L x B x D x 0.16 for motorized monohulls <15m in length
c) Appointed Tonnage - measured by a professional

Pertinent links are:

Transport Canada - Tonnage Measurements
https://www.tc.gc.ca/eng/marinesafety/o ... e-1515.htm

Form 4A Simplified Method of Tonnage Measurement
http://wwwapps.tc.gc.ca/Corp-Serv-Gen/5 ... er=85-0405

Links may change over time, but searching the title may dig them up.

Anyhow, my calculation for a 22 Cruiser's Gross Tonnage (Transport Canada - Simplified Method) is:

Length: 6.7m
Breadth: 2.3m
Depth: 0.9m
Gross Tonnage Coefficient (motorized monohull <15m): 0.16

6.7 x 2.3 x 0.9 x 0.16 = 2.2 tons

Alternatively, 4.99 tons using the Assigned Formal Tonnage, if I feel like rounding up.

Thanks all!

Ctarmigan
 
I’m sure they don’t really care what you put down. The formula I use is throw in a ton of gear and go out every chance I get. Keeping the heavy thinking and stress at work. See you out there somewhere.
 
That will definitely be my formula, too. Having just returned home from overseas (my family and I had an unexpectedly extended stay in New Zealand), I'm currently in quarantine, with nothing to do but sweat the small stuff.
 
Missynme":1fmp8lbm said:
I’m sure they don’t really care what you put down.
Click to expand...

I'm hoping this is the case. When I bought my trawler, the broker sent the documentation paperwork off to a documentation service. I had heard over the years that this was an expensive and largely unnecessary service, but I had also heard that they get it done faster and one isn't supposed to use the boat until the documentation is complete. $400. The problem was more in the accuracy of the service. I received a first draft and had to correct some of the data. I didn't catch all the mistakes.

Builder specs for my boat are 17,000 lbs. That's what was on the prior owner's CG documentation. Mine issued and now reads 17 gross tons. Now that's a heavy 30' boat. I don't think anything (fees, etc.) is based on tonnage, so I let it be.

I haven't applied for my MMSI yet (1990 era VHF doesn't have it). Based on the document weight, the CG would think that my 30' trawler has a 6' draft and 6" of freeboard.

Mark
 
Reefmadness is US documented. This was required to obtain an Alaska Commercial fishing permit for her. I did the calculations, sent MSO and Building diagram to CG Documentation center in Falling Waters WVa. It was calculated to be 8 Net Ton. Outboard motors eliminate the adjustment for motors.
 
Requiring Gross Tonnage for a 22 cruiser is an oxymoron - as would be
Gross Domestic Product (GDP) for a barber's license.

Aye.
Grandpa used to say, "Some rules are meant to be broken."
 
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