Re: [bolger] Re: Registration/Documentation.
No, sir. The measurement of tonnage for regulatory purposes (including documentation) is based on volume of usable enclosed space, and has nothing to do with weight or design displacement. The relevant instructions and formulae may be found in USCG document TG 1 CH-2 Simplified Measurement Tonnage Guide 1(item 4 in the Supporting Documents menu at https://homeport.uscg.mil/mycg/portal/ep/contentView.do?contentTypeId=2&channelId=-24502&contentId=46732&programId=46748&programPage=%2Fep%2Fprogram%2Feditorial.jsp&pageTypeId=13489&BV_SessionID=@@@@0201133896.1343673388@@@@&BV_EngineID=ccceadfhghddhjhcfjgcfgfdffhdghk.0 ). See page 7 for simplified Gross Tonnage and page 9 for an adjustment to get Net Tonnage. There is also a much more complex process for calculating tonnage, but for our sorts of vessels that complication is not required.
The Gross Tonnage is the estimated volume of hull plus deckhouse in cubic feet, divided by 100 cubic feet per ton. The Net Tonnage (which is what needs to be at least 5 tons to document your boat) is the gross tonnage reduced by a factor for propulsive machinery, depending on kind of machinery and vessel.
Two otherwise identical boats can have substantially different tonnage if one has been built with higher freeboard (thus greater hull depth) and/or has larger deckhouse(s). Also, a boat with an inboard engine has a lower tonnage than an identical boat with an outboard, because the inboard engine takes up some of the usable volume.
--- On Mon, 7/30/12, sirdarnell <sirdarnell@...> wrote:
From: sirdarnell <sirdarnell@...>
Subject: [bolger] Re: Registration/Documentation.
Date: Monday, July 30, 2012, 12:09 PM
This is correct, 5 tons is the design displacement of the boat not it's weight. I.e. how much the boat and all contents and people on board would weight if boat is filled to the maximum (people/supplies/equipment/fuel) the designer intended it to carry.
--- In email@example.com, "loosemoosefilmworks" <loosemoosefilmworks@...> wrote:
> Well for one don't get hung up on the 5 ton thing as the USCG definition is mostly derived by volume. We had no trouble documenting our first Loose Moose (a Jessie Cooper design) which at 25 foot and a kiss is quite a small boat.
> Down here in the Caribbean the only islands that are currently problematic and require USCG documentation are the French ones but everywhere else is OK with state...