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Trawler market?

Discussion in 'General Trawler Discussion' started by olderboater, Feb 18, 2019.

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  1. Beau

    Beau Senior Member

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    So the nice thing about us is that I can run at 5.7 knots with one engine. Horrible when we come into that 5 knot navigational channel I look like a fool in and out of the throttle spinning the wheel to keep control. But I do love the economy when we are on a 7 day cruise to the Vineyard. I run 30 when I need to and 10 when I want to just put a mustache on her - boating is my drug of choice!
  2. JWY

    JWY Senior Member

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    Can you quote some statistics on this rubbish?
  3. Capt J

    Capt J Senior Member

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    Most all traditional trawlers are displacement hulled (OA's, Marine Traders, Kady Krogens, Grand Banks). Sure, it's simple math. The length of a displacement hull is what by far determines it's maximum speed. From my experience a 32' displacement hulls, hull speed (speed through water, it you're against a 3 knot current it will slow you down almost 3 knots in SOG) is around 6.2 knots.....a 42' around 7 knots, a 50' around 7.5, a 60' 8.2 knots. So in a 60' trawler if you're against any current, which is usually half of the time, it's going to slow you down from it's maximum hull speed. PLUS, if you run the vessel right at 8.2 knots a lot of very undesirable handling traits usually present themselves, not tracking straight, strange movements, and sucking bottom, so most Captains and owners cruise displacement hulled boats slightly below maximum hull speed at say 7.5 knots.

    Here's the formula that determines speed on a displacement hull. The hull will NOT exceed this speed, regardless of horsepower. It's simple physics. And the naval architect will know the exact speed when he/she designs the hull. If you are a broker that specializes in trawlers and do not understand this, I am speechless.

    Displacement hull speed formula
    The SL Ratio is a simple formula for calculating displacement hull speed which is typically 1.34. Velocity = (g * Length / 2 pi) ^ ½. g = acceleration of gravity (32.15 ft/sec ^2) Convert ft./sec. to Knots and the result is 1.34 * L^½.
    Last edited: Feb 27, 2019
  4. JWY

    JWY Senior Member

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    Aside from talking about ratios, there is so much blatantly wrong information in your posts, I finally had to respond. I have sold over 200 trawlers/fast trawlers, perhaps half of those have been full displacement vessels. If I have been on sea trial on 100 full displacment yachts and I have speed logs from owners, I think I am entitled to disagree with what you propose as factual information when it is mostly garbled misinformed opinions. What's with the running at 8.2 knots means undesirable handling with all of your descriptions? What have you been driving or smoking? And you're now speaking for most captains and owners? Stick with your opinions of motoryachts, please. I can't correct everything you have stated that is just plain INCORRECT!
  5. Capt J

    Capt J Senior Member

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    A "fast trawler" is not going to be a displacement hull, it cannot be. I am talking about displacement hulled trawlers exclusively, which I was very clear about in my initial post.

    Nothing is incorrect. It is all proven physics dating back to the 1900's or earlier. Sucking bottom is a very well know and common phenomenon. It effects some non displacement hulls as well, but not nearly to the degree it does displacement hulls. It effects virtually all displacement hulls, do to the fact that they displace the water. If you're tooling along at near hull speed in a displacement hull and get into a shallow area with only a few feet under the keel, it will make an instantaneous extremely hard turn usually towards the shallower water. To correct that, you back the throttles way down and give considerable counter steering. I suggest you study hull designs and how it correlates to operation. Horsepower does not make a displacement hull faster, a displacement hull has a set speed through water, based on the formula I posted above and no amount of horsepower (aside from that which is needed to push it to it's displacement speed) will make it go any faster. Any of your displacement hulled trawler owners that travel in places where they could get in shallow water, like the ICW will confirm this.

    If you are running right at the hull speed in a displacement hull and hit a counter current, most displacement hulls will plant the bow and the stern will try to come around as that's where the hull is being propelled from, I've run several that have done a 180 degree turn in 2 boat lengths.

    Just like a sailboat has a faster hull speed/displacement speed when it is under sail. I bet you cannot answer this either! It is because when a sailboat is heeled over, due to it's rounded hull sides, has a longer waterline length, which increases hull speed.

    And of course speed logs will be different. If I'm taking a trawler North and have the gulfstream with me, you can add that speed to the hull speed! I've DRIFTED 5-8 knots in places with the engines in neutral because of the speed of the current.

    Please go back to selling boats, instead of trying to educate people on simple physics relating to the boats that you sell, which you clearly know nothing about. There are many good books out there that can educate you on hull designs and their handling traits that are inherent to each hull design. Even a book as basic on hull design as Chapmans will have this information in it. How can anyone be good at what they do, if they don't know the basics of why the product they're selling, does what it does?
    Last edited: Feb 27, 2019
  6. JWY

    JWY Senior Member

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    Sorry, you're way off in your accusations. I was determined to not respond to any of your absurd posts and I blew it. I don't want to get into this again with you, so I will take the gentlemanly course and drop out. I don't know how you sleep at night advising people on things as serious as boating and being so off.
  7. chesapeake46

    chesapeake46 Senior Member

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    Amen.
    And I wish I could " up the dose "
  8. Beau

    Beau Senior Member

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    Indeed, getting pretty heated above us. I may need cotton balls too....
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