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Thursday, May 8, 2014

Nordhavn build questions

I was asked a question about our Nordhavn build, and thought it would be better to answer in a post rather than a comment.  Here's the question:


Anonymous Anonymous said...

It is fun watching your build and seeing some of the custom things you are doing. I noticed no bulbous bow and know that the first several N60's were without, but thought PAE intended to make that a standard. Did you opt out? I believe you came to the correct conclusion, but would be interested in your thought process. One thing you did that I debated when having my (non-Nord) boat built was all hydraulic windlasses and thrusters. In the end, I concluded that the cost ($40K extra, as a change order on my boat) wasn't worth the benefit.
I see you went with a gas range, as did I (although I was cautioned it was a bad idea). I have no regrets about that decision. Can't wait for the next installment. -Rick
So the questions are 

1) bulbous bow

2) hydraulics

3) propane vs electric cooking

Bulbous Bow:

PAE has a good article on the topic on their web site where they talk about some of their key design features Nordhavn construction fundamentals.  As best I can tell, the 50, 57, and 62 mostly or all came with bulbs, but in the latest generation of models they are not available until you get to 76'.  Read the article for more info, but bulbs are not without their down sides.  They work best when tunes for a specific speed like a freighter operates, but for a boat that operates at a range of speeds they can harm as much as they help.  They also can create slapping in certain seas.  I read about one owner who added a bulb to his boat, then cut it off the next year because the slapping was so horrible.   PAE seems to have been wise to focus use of bulbs only on the larger boats.  The down side of not having a bulb is that you can't do fun things like this


Hydraulics:

Hydraulics also have their pluses and minuses.  The plus is that it enables more powerful thrusters (25hp), and you can run them continuously.  Electric thrusters heat up when you operate them, and after a while trip a thermal breaker.  You need to run them for a minute or more to get a thermal timeout, but if you are running them that hard, it's probably because you really need them, and that's the worst possible for them to shut down on you.  I didn't want that.

Additionally, an hydraulic windless is more powerful than an electric one.  I didn't know this going into this project, but rather stumbled across it later while reading the specs for my Maxwell 3500.  The "3500" means it can lift 3500 lbs, but that's only for the hydraulic version.  The electric
 version can only lift 1200 lbs.  Both are enough to lift a 200lb anchor and 400' of chain, but the electric version can just barely do it where the hydraulic model can lift it with ease.

One more key point is that assuming you have stabilizers, you already have hydraulics.  It them becomes a question of what you are going to do with them.  Granted, it takes a lot more capacity to run thrusters than stabilizers, but you are taking on the extra complexity either way.  Pat of that complexity includes a few failure modes that can disable all the hydraulics.  This is a common argument in favor of electric hydraulics and winches: as independent devices, failure of one won't disable another.  This is true, so part of having hydraulics is understanding these failure modes, doing all you can to prevent them, and being prepared in the event they happen.

Propane Vs Electric:

There's no doubt that getting rid of all propane on a boat eliminates the possibility of a propane fire or explosion.  That's good of course.  But to me a grill isn't a grill unless it's gas.  And I greatly prefer cooking with a gas cook top.  And it's nice to be able to cook and grill without having to run a generator.  So gas it is for us.

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