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samN 07-09-2010 08:00 AM

Horsepower requirement of the tug towing the barge

I have a question.. I hope I will find the answer in this great forum that I browse regularly

Is there any rules to calculate the hp of a tug depending on the barge tonnage or capacity ??

If there is no rules .. how can we determine the tug's power according to the barge's tonnage ??

Submarine Tom 07-09-2010 09:58 AM

It depends on many variables.

We need more information.

How did you get this job if you can't do it?


apex1 07-09-2010 10:42 AM

You first have to find out the resistance (wave drag, skin friction, etc) your tow produces. Then you need the speed you like to move it.

Then you can start a power estimation.

Are the missing parameters available?


samN 07-09-2010 10:46 AM

Thank you Tom .. actually I'm a Safety Officer:p
Thank you apex1 I'll try to find out that !

rxcomposite 07-09-2010 06:36 PM

I have the formula but my bags and PC are packed. I will try if I have it on USB. It is about the displacement of the barge, the wind resistance above waterline, and the sea state where it is going to operate,

Not your job. It is a surveyors job or a Naval Archie. Tell your boss to pay a marine consultant specializing on this fiels.

samN 07-09-2010 07:25 PM

Great !! thank you rxcomposite..hope to hear from you soon

rxcomposite 07-10-2010 01:41 AM

I may be far from this one. What i have (or rather don;t have) at the moment is a simple spreadsheet for calculating tow Hp of a marine vessel. Not even explanation or rules. It is like lifting a page from Naval Architecture book.

Crag Cay 07-10-2010 03:24 AM

There are standard procedures for calculating bollard pull (normal sizing method for tugs) for a given towing job. You simply have to check that your operator has such a method in place and is complimented by a sufficiently rigourous Standard Operating Procedure (including record keeping) that your boss can have confidence that it meets any statutory requirements.

This link is to one such method spelt out be Guillermo including a rough translation from bollard pull to the less useful HP if needs be.

rxcomposite 07-10-2010 09:56 AM

I have it but cannot post it as it is not entirely mine. It is very easy to use even a non NA can use it. Unfortunately, I cannot even send u a private message. Send me a private message if you do not want to post your email.

apex1 07-10-2010 03:01 PM

The method by Guillermo (link by Crag) is more than sufficient to come to a very close result.


rxcomposite 07-10-2010 03:48 PM


Of course. In fact I am taking a look at it right now. I am just giving what I have for whatever use it maybe to him because I promised him. Let him do whatever he wishes.


samN 07-10-2010 04:29 PM

TOW to HORSEPOWER procedure
I appreciate everyone's input.

rxcomposite 07-10-2010 05:36 PM

Thats correct. You have to know if the tug has enough bollard pull to pull the barge/rig, whatever it is towing and the sea condition it will be operating on. You have to download the forecasted sea condition you will be operating on.

In our case, we were hired by the charterer to send a surveyor to do a condition survey of the tug. Things like condition of towing cables, shackles, machinery, quick release, ect. At the same time, there was a company safety officer doing the same thing which I beleive would be your job.

Are you a ship safety officer for the company that owns the tug or are you the charterer that commisioned the towing?

samN 07-10-2010 09:41 PM

I am a safety officer for a company that runs barges. I was confused about what is meant by this ratio! I used to serve on ships.

rxcomposite 07-11-2010 02:29 AM

Well, good luck to you. Over here in the gulf, safety officers work 24/7. you will never know when the ship is coming.He has to make sure all ship's certificate is current, all firefighting equipment and lifesaving equipment on date. ect. Lots of paperworks. It is very similar to the safety policy/procedure posted on the ship you were working before. Assuming you were working as a deck officer. They assumed you know.

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