Entering Nicaragua

I spoke with Jeff on the boat earlier this morning. He was just leaving costa rica and running north along the coast of nicaragua. On our run south, we had left a “track” on Nobeltec, and he was following our track. When I spoke with him he was 5 miles off shore, and in heavy rain. He said it had rained virtually non-stop all night, although overall it was not bad cruising conditions. The winds are under 5 knots, and he isn’t fighting a current. When we spoke he was making 9.5 knots, at 1,350 rpm, consuming just 14 gph (including the generator).

He did have a small incident yesterday afternoon… For no apparent reason, the stabilizers suddenly failed. With a 8-10 foot beam sea, this was NOT fun. He couldn’t figure what was happening, and called both Nordhavn and ABT (the makers of the stabilizers). We were on a bad sat phone connection, so I’m not 100% certain I understood what he was saying about the problem .. but, my understanding is this:

There are sensors on the shafts that tell the brain for the stabilizers what the engine rpms are. I’ve had problems with the shaft sensor failing intermittently. My guess is that the stabilizers thought one or both shafts had stopped turning. ABT had Jeff put the stabilizers into “manual mode” and suddenly the stabilizers worked fine. So .. after a couple of hours of being tossed around, all was fine again.

On a completely different topic…

I’ve been discussing props with another Nordhavn owner, and how prop pitch relates to efficiency. The other Nordhavn owner asked how “load percentages” I was seeing.

I must confess that I don’t at all understand the load percentage numbers. The engine murphy gauges show the load percentage, but I’ve never known how to interpret it. I asked Jeff what the engine load was, and he said 40%. Does this mean we are wasting 60% of the power being passed to the props? If someone reading the blog understands this topic… explain it to me below…

Thank you,
-Ken W

4 Responses

  1. Rod:

    You are right about Hundestat props. Were I building a boat today I’d almost certainly go with them. I might think about switching this winter. There’s no way to know, but I bet I’d extend range by 5-10%, and be able to run single engine if I want, without fear of burning out a transmission.

    My only fear is of their complexity, and getting repairs in third world countries…

    -Ken W

  2. I believe the load rating display is the percent of power the engines are currently generating(how hard they are working) to move the boat at present. A load rating of 40% means you still have 60% in reserve at that point. If you were around 80% to go the same speed you may have put in the wrong engines or wrong pitch on the wheels.

    It might be worth noting this number from time to time. I imagine if the number slowly increases(so will the fuel rate) you might want to have the bottom cleaned. If it changes drastically, you should unhook those nets you snagged or maybe you forgot to untie that aft mooring line.

    Enjoying the reports- thanks!

  3. Ken:

    Just a thougt

    If any one should know it is Hundested who make variable pitch props – Norhavn has spec’d one for the 56MS

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