Calculation of GT (Gross Tonnage) Help Needed

[landbound]

Can anyone assist with regard to the measurement of GT (Gross Tonnage) for a catamaran sailing boat of approximately 14 Meters

I do understand that most boating countries have a simplified calculation applicable to pleasure boats and in the case of the USA for craft below 5GT. This is not the case for Indonesia where the measurement is required.

I want to own and sail a catamaran in Indonesia. The Indonesian shipping Law 17 / 2008 is clear that only an Indonesian may own or sail a boat avove 7GT. Thus any boat I build or buy must be below 7GT. I am fully aware of the CAIT that permits foreign flagged vessels to cruise Indonesia, however I am not looking for avoidance strategies however useful they have been for others.

Anyone with a knowledge of International Convention on Tonnage Measurement of Ships, 1969 will realize it is purposed for cargo ships and to a lesser extent for passenger ships not for pleasure craft - thus an enthusiastic amateur is unlikely to get any calculation right, - not because the calculations are difficult but becuase the defintions are really unsuitable for catamarans - the full horror of the measurement methodology can be viewed here - http://untreaty.un.org/unts/60001_120000/21/34/00041700.pdf

I am delighted to pay a professional to perform the calculations and would supply cad drawings that would allow the determination of internal volumes. That person must be "a competent person or organization recognized under the provisions of the international treaty" my guess is if you don't know if you are then you are not !

For me to engage such a person I would want evidence that they are authorized to certify by their relevant national authority and that they have some experience calculating GT on pleasure craft using the full treaty method not for example the US Coast Guard "simplified" calculation. With the greatest respect to any marine surveyor reading this, years of experience with tankers and bulk ore carriers is unlikely to be helpful. What will help is practical experience with the relevant authorities and knowing for example what the authorities view of the definition of a "deck" or "stepped deck" is with respect to a sailing catamaran.

Equally welcome would be a contact that you know might be versed in such arcana.

If you have managed to get to the end of this incredibly dull email I thank you and ask you to shed a tear for those who wish to sail legally in Indonesia without resorting to classic third world "fixes".


Guy Warwick

[RAraujo]

The ITC 69 is not applicable to boats under 24m (although some adaptations have been made in some countries, like those of EU, to extend its application).
Most probably Indonesia will have their own regulations for calculating the tonnage of pleasure boats/boats under 24m). Check with the authorities which regulations are applicable - most probably there will be a simplified calculation (even if measurement is required).
Measurements are required probably because most of the local boats are tradicionally built without a set of plans from where you can obtain the measurements.
You can try to contact also one of the classification societies' local offices.

[landbound]

Many Thanks there are no pleasure boat regulations in Indonesia other than a tax code for their importation. A simplified calculation does not exist as stated in my first post. The 24 metre rule is an exception to the 69 convention it is not an exception to Indonesian Regulations where calculation as per the convention is necessary to meet the 7GT test. Very unreasonable but that is the law.

I have already approached a local surveyor and as I expected they have never had to calculate GT for a pleasure craft.

Do you know anyone in your jurisdiction who might have experience with such a calculation on a sailing catamaran

Thanks

[RAraujo]

So it seems they are following the same scheme as the EU countries...
The tonnage is quite easy to calculate - you just need to have the whole enclosed volumes of the boat. If you have a lines drawing and a general arrangement I can do it for you (for free) and without any warranties that it will be accepted.
Anyway I've asked an idonesian naval architect, who is a friend of mine, to clarify this and I will get back to you if there are any news.

Rodrigo

[landbound]

rodrigo you are very Kind I have PMed you my email address