Operating Cost of 70' Steel Fishing Vessel?

Of course... I thought there was a typo. Multiplying the numbers you gave by the distance traveled in that same hour (by 9 in the case of 5.2 liters) is much more in line with figures I've been seeing. Thanks.

 

Not at all. As I said:

find the boat, then we can guess.

 

Sorry, I don't understand what more information is required. I gave you all the dimensions of the boat and pictures of the underwater profile above... is there more needed to make the guess? Dry weight? Please let me know and I will supply all the data required.

Thanks!

Also, I am now coming up with prices of $5000 or so in one direction to move the Malahide between the same locations at 7kts.

 

We are talking just out of the blue sky here.
There was no boat shown which we could discuss, just several different examples without any data.
And even then I would not discuss them.
you have to find a boat that fits your bill, then discuss if it is worth thinking further.

What is it worth to make estimations for a 150 tonnes boat witha Cummins KTA 19, when you buy a 120 tonnes one with a Lugger of twice the power?

If my Malahide Trawler is already in the 5000$ consumption range on your trip, you may safely guess, that a commercial fishing boat will be substantially above that.
As I said before, they are often powered much north of what you need.