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Thanks to "North Baltic Sea" for providing data. From the looks of it, the behavior of the SD hull is pretty typical, I would think. It is obvious that one would be strongly tempted to cruise at 8kts or less, or if in a hurry, go to 14 kts. Any other speed is very expensive per hour saved. Looks...

Thank you very much. I'll put it into my spreadsheet and publish the results.

Well, that was sort of my point. Neither dollars nor time are infinite. Therefore, whether out in the open or not, we all compare the relative value of our time and the dollar. For some, $1000 of operating cost is virtually meaningless, while for others it might be felt to be huge. For some an...

Chris, Using your numbers (6.5kts@3mpg and 7kts @2mpg) I come up with the number of $45 per hour. That is, it costs $45 for every hour saved going 7kts instead of 6, all assuming $3/gal for fuel. That sounds fairly expensive for going 7kts instead of 6. And BandB said his boat costs $61 at 15kts...

Maybe this should be in a different thread, but I've a comment on the "cost of speed". I've calculated this for several vehicles, including my Nordic Tugs trawler. Here's the jist of it: If you are going a given speed and burning a given amount of fuel, how much would it cost if I changed the...

Just to add what might be useless information, I like to evaluate what's known as "propulsion efficiency." That's nothing more than the speed of the boat divided by the speed it would go if the prop was not slipping in the water. The efficiency of my sailboat prop was about 55%, my tug is 65%...

One comment I read was about connecting batteries with significantly different charge states or voltages. While under charge (current coming in) the voltage will be fairly high - like 14+ volts. When below full charge the voltage can be as low as 10 or 11 volts. Connect the two together and, yes...

All the posts were interesting, but I think I'm commenting primarily on the post from FlyWright. I tried to add a figure, but it didn't work. In my single-engine system, the as-modified system The start battery(bat2) connects directly to the engine starter, engine panel, thruster and windlass...

NT 32 hard chine The noise generated by the hard chine was disturbingly obvious the first night I spent on the boat. I too thought about how to fix it, but it looks like your modification is the only true fix. It looks most excellent from the pictures. I wonder why NT bragged so much about the...

Battery wiring configuration First, I don't see where there is a "large surge" of current when the ACR is activated. If one battery is being charged to some voltage and another battery is connected to it, there will be a current flowing between the two, but it won't be dangerously high current...

Engine oil level There might be a lot of overthinking going on. I'm certainly not an expert on much of anything, but here are my opinions: First, don't check the oil with the engine running. The fill level was set by the manufacturer assuming the engine is shut off, not running. Also, I...

Here's my thought on the matter, not that my thoughts are worth any more than you just paid for them... I would connect the engine starter directly to the start battery, along with the engine controls. I would also connect the thruster and windlass to that battery. The idea is that those...

Engine size To me, there are probably 2 important reasons to "oversize" the engine: The main one is that assuming the engine, prop and boat are matched to allow maximum speed at maximum hp, The oversize engine will allow cruising at a much lower rpm and noise level. Mine will top out at 2600...

Yes, it depends on which fuel pump is installed. I think the multi-piston (like Bosch) pumps have stop solenoids and ones like mine with the Lucas CAV pump us "run" solenoids. Which brings up a question of mine. I noticed that the original stop lever is still there. I want to eliminate the run...

I would bet that the reduce "vibration" is due to the better (although I'm not sure what it was like to begin with) airfoil shape and the smooth rounded leading edge that is bothered less by the pulsations in the propwash. Going by airfoil characteristics, the center of pressure is usually in...

Interesting design. However, you imply that you can put the helm hard over at full speed AND turn with less than 5 feet of forward travel. I think you meant that you meant to replace the AND with OR. If I might summarize (correct me if I'm wrong) there are at least 3 features that are important...

I believe the theory behind this is that the boundary layer thickness increases toward the aft end of any surface. Bringing the edge out through this boundary layer increases the sensitivity of steering. How thick? Don't know, but I suspect not nearly to the extent I have seen of the proposed...

Loose connection Don't forget to look at the simple things first. It looks like you have verified that you have enough battery and the loads are small. I very much doubt that your "good" batteries would suddenly not be good after a couple of hours running normal loads. For a short stop like...

Cost of time The discussion on speed vs. range was very interesting. I went a step further and calculated the cost of time. The calculation gives the answer to the question, "What would it cost me to save an hour on this trip?" For example, we usually cruise at 1300 rpm, which give about 7.4...

I certainly agree with the posts above that disagreed with my post about fuel cost. Yes, if you are rational and spread the cost of operating a sailboat over the miles it has traveled it is pretty expensive. After all, a new main can cost $5,000. But I'm talking psychology. The dollar you spend...

Thanks Art, Yes, I've been a sailboat(s) owner for maybe 20 years, graduating up to a 34 Hunter. Since then I've been a "borrower", sailing our son's boat (J110) for 2 weeks every year. This Nordic Tug is our first trawler. Looking forward to it!

gasoline vs. diesel as a fuel I'm new to this list, and am just in the process of buying my first trawler, so I have no experience to draw from, just my engineering background. First, hp vs. torque: This argument has gone on forever. Hp is simply torque times rpm, so they're not exactly...