Fishing and Sensoring

Nordhavn posted a couple of pictures on their website today of their new 75′ Sportfisher.

I’m curious to see how it does. I personally think it is going to do very well, even though it seems to violate one of the cardinal rules of sportfishers, which is that “it’s all about speed.” Whereas us trawler folk are happy to plod along at 8 knots, the sportfisher audience believes 25 knots is where it is at.

However, in my opinion, there are a few reasons why I believe this boat could be a big hit for Nordhavn:

1) Range. This is a boat with a 3,000 nm range! Most sportfishers have under 500 mile range. This allows the owner to go places others can’t. I know that on my boat, there is a clear difference between fishing around big tourist areas, and in places no one goes. A lot of popular destinations have been “fished out.”
2) Comfort. Boats are expensive. Generally speaking, the bigger boats are bought by people who are well into their careers, or are retired. As we get older, comfort matters more and more (at least at my house!) This is a boat that lets you go long distances in style.
3) Fuel consumption. Don’t let the recent price drop for fuel fool you. Miles per gallon counts. This is a boat that uses a fraction of the fuel other boats do.

I don’t fish, and am not a target buyer for this boat .. but, I like the idea, and hope it does well.

As to my boat…

I mentioned last week that I’ve been working on finding flow sensors, so I could measure the fluid coming and going from my sea chest.

I ordered one flow sensor, which came in a couple days ago:

My hope, reading the ad, was that it could measure raw rater flow through my cooling system. It might do this, but my first reaction upon opening the box was disappointment. This particular sensor was comparitively inexpensive (only $400). However, it is large and feels clunky. It is about 7 or 8 inches long, and has standard hose fittings at each end. I’ll have to be creative to plumb it into the system, and I don’t know I’ll have the space to put the six of them that I’d like to install. Worse yet, I had interpreted from the specs that it used ultrasonic technology. I don’t want anything that interrupts the flow of the water. Unfortunately, when you look at it closely, it has a place where the water flow is narrowed. It measures the pace of the water by funneling it through a narrowed pipe. This is an opportunity for clogging. I remember from my college days an old saying that it is impossible to monitor something without influencing it. This seems to be particularly true in this case. And, adding to my doubt that it will work as I want, there is a paddle wheel! I wanted an ultrasonic sensor so that I could measure the cooling water without slowing it down. I don’t want anything that might harm the flow of water.

I have another estimate from a company to do the measuring, in a way that does not impede the flow of cooling water — but, it is expensive. Why is nothing ever easy?

-Ken W

PS And, lastly… There was another pirate attack today against a freighter. The most amazing thing about this one is that the pirates attacked the ship FOUR HUNDRED AND FIFTY MILES OFF SHORE! When we ran Nicaragua my plan was to run 20 miles offshore, in order to beat the pirates. I now see that if they want you bad enough, they’ll come get you. I wonder how the pirates knew the ship was there? AIS? Radar only has a 30-50 mile range. Perhaps the pirates were just floating, waiting for a good target to come along? 

8 Responses

  1. Here in Eastern North Carolina, we have larger fishing trawlers with half-pipes welded for 60 to 80 feet on there bottoms. These are their keel-coolers. Fernstrum and others use multiple pipes to achieve the same thing in less space on fiberglass and metal boats. Some folks employ a wet exhaust for these systems by injecting raw seawater into their exhaust systems to create a hybrid. It is my belief that the volume of seawater used is less than what would be used by a water cooled system.

    Looking at the language used in the document, I believe that the sensor you found was made in China or maybe here by Chinese speakers because that’s the way they write English. This could explain why your vendor incorrectly described the sensor. It needs to go back.

  2. Ken,

    I believe keel cooling is used in many large boats-think tankers, freighters, ferries, etc. These boats also all use dry exhaust. My understanding is that you can have keel cooling and dry exhaust or not have keel cooling and have wet exhaust. Perhaps someone else knows more about the issue, or Dan (or another Nordhavn employee) could chime in…


  3. Adam: Yes… the sensor you found is almost certainly what I’ll need to go with. The advertising for the one I bought implied that it was non-invasive, but the reality was far different than the advertisement. Too bad: it was a $400 sensor. The true ultrasonic sensors, such as the one you suggested, are expensive. The cheapest I’ve found is $1,295. I have a bid from one company to install six sensors that is over $10,000, and I am fairly certain they would be doing it at or below their cost – because they believe in the category, and this would be a highly visible project. It’s a bunch of money, but my current leaning is to go for it, if I can figure where to put the sensors. Unfortunately, the spending doesn’t stop there. Once I have the sensors, I still need to pay the Simon people to do the integration work.

    As I’ve said before, this is not necessary, and I would be the only boat doing this. So.. it could certainly be argued that it is money wasted. My justification (aside from the obvious fact that I like electronic gadgets), is that we will be circumnavigating in strictly warm water climates. My theory of diesel engines is that they very rarely fail if you just “keep them happy.” If you give a diesel engine clean fuel, keep it full of clean oil, and maintain a steady flow of cooling water – you are VERY unlikely to have problems. I don’t like problems, and raw water is inherently a problem. It is very easy to suck a jellyfish into the system, or have barnacles grow inside hoses. I want to know immediately of any impending problems before they start destroying expensive machinery.

    An interesting side note to this discussion is: Keel Cooling. Most Nordhavns use keel coolers for their cooling water needs. This is a closed loop system, which goes to something that looks like a radiator, mounted on the keel of the boat. I’m not sure why Nordhavn’s larger boats don’t use keel coolers, but assume that it is because they aren’t practical for a boat my size. Too bad…

    -Ken W

  4. Ken:

    This line from your flowmeter’s manual is not encouraging: “The suspension and the impurity can not exist In the liquid, otherwise the current sensory hole will be blocked, even generating inaccuracy or loss of function”. (sic, sic, sic)

    Any reason you’re not using a Doppler flow meter like this one? (

    The tech specs (pipe size & type, compatible fluids, etc.) seem appropriate for your application. I wasn’t able to locate a price online.


  5. Scott: I have researched pressure sensors, and if there is one out there that works, I haven’t found it yet.

    I do plan to use a pressure sensor on the seachest itself. I’m a little worried that it will become gummed up almost immediately. Most of the pressure sensors work by having a sensor that you screw into the pipe holding the liquid. In my case, it is raw sea water, and the odds are the salt water will gunk up the tiny opening in the pressure sensor in days. I have searched for a pressure sensor that uses ultra sonic technology, so that it wouldn’t actually be immersed in the water, and not found one.

    My other issue with pressure sensoring is that I would think I want to do it close to the device which is receiving the sea water; for instance, at the water maker, or generator. This scatters the sensors around the boat. If I put the sensor too close to the seachest, I’ll be seeing the pressure which is inside the sea chest, not the pressure within the hose that feeds the device that is consuming the water.

    At this point, I’m a little stumped … so, if you want to try some googling, all help appreciated!

    -Ken W

  6. Ken,

    Two thoughts. First, can you monitor water flow by monttioring pressure. If there were a pressure senor somewhere in line, and pressure decreases, then you would believe that volume might have decreased, hence restricted flow?
    The alternative option is to put heat senors on those items that should be cooled and track temperature as a proxy for flow or restriction.
    I am sure you have thought about these, but I would love to know why they wouldn’t work


  7. Hi Ken,

    Thank you very much for the kind words about our new EYF75. Yes, until now, sportfishers have been high powered monsters and it has been all about speed- but for reasons that many people outside the tournament fishing world don’t realize.

    In fact, the proper speed for trolling and fishing is about 8-10 knots and most sportfishers travel around on deliveries at displacement speed (when is the last time anyone has seen a big fancy sportfisher traveling at 25 knots while on its way to Cabo?).

    The high speed performance characteristic of the typical sportfisher is for the sole purpose of single day tournament fishing. A bell sounds at 5:00AM and a fleet of gleaming monsters roars off from the yacht club for a day of fishing- returning by the deadline of 5:00PM for happy hour and to weigh the day’s catch. In this circumstance, of course speed is essential because it allows the boat to cover more area and reach the best fishing spots in the allotted amount of time.

    Other than that one magnificent quality (speed), the modern sportfisher is a rather laughable creature. In the extreme cases, they have little or no anchoring ability, no dingy storage and their need for weight saving starves the boat of important cruising equipment and luxury.

    We know that at this point, we have produced a boat which the market doesn’t quite understand. But, we have been there before. The N46 was an “ugly duckling” and confused people when it was first introduced in 1988. The N46 is now venerable and in hindsight, it is not a stretch to say that it was ground zero of the “production” small expedition boat. We expect the EYF75 to have the same kind of evolution of awareness as models larger and smaller are developed in the coming years. 20 years from now, we will look back and say.. “duh, that was so obvious”.



    PS: We also envision the EYF in other iterations. With a few easy modifications, the EYF could be the perfect “adventure” boat for diving and exploration and we expect to develop a “European” version which should be popular in the Med. As you know from your time in the Med, those folks like a big cockpit for sun bathing and like to “see and be seen” while stern tied in the perfect Mediterranean marina.

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Credits     |     Video produced by: Rock Steady Media     |     Teletype photo: Arnold Reinhold     |     PDP-11 photo: Trammell Hudson