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Deep Vee versus Semi or Full Displ.

Discussion in 'Yacht Designers Discussion' started by TimL, Jan 5, 2011.

  1. TimL, Jan 5, 2011
    #1
    TimL

    TimL New Member

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    Hello,
    I would like to know if any Builders or NA/Designers has info on the performance (specifically rough water) between the deep vee designs verse semi or full displacement. Example - how will a Grand Banks Eastbay (deep vee) handle 6 foot waves in the NW verse a Nordic Tug (semi displ.) verse Kadey Krogen (full displ.). I see most pilot boats, rescue boats are deep vee and they have to work in any weather. But everything I see in literature and on-line say full displacement is best in rough water.

    I'm asking this because I like the appeal of having a quicker cruise speed (12-15 knots) in a Eastbay. This would get us to our destination quicker or extend our range for weekend trips. We have a Nordic Tug now and it is fine, but would like to get a larger boat with two staterooms. I would not want to buy an Eastbay and be dissapointed by the rough water handling. Our Nordic Tug can handle rough water but is isn't large enough for really nasty weather (ours is a 32' and the we have been in 6 to 8 foot seas and it was not fun, but we survived). How does the deep vee compare with the others mentioned above?

    Thanks for any info.
    Tim
  2. NYCAP123, Jan 5, 2011
    #2
    NYCAP123

    NYCAP123 Senior Member

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    With the Deep V you'll generally rock more at slow speed and at anchor, but you'll rock less when going faster. Full displacement will give you better stability at slow speed and at anchor, but doesn't give you speed to aid stability. So you have to play the waves more when in the big stuff, and you're a bit of a victim. Semi-displacement is a compromise. I'd think more about whether I prefer fuel economy and range vs speed, and then sea trial some boats. 6'-8' in a 32 Nordic? Love 'em, but :eek:
    Love Kadeys, and would go there if my plan was long distance cruising or living on board, but as a weekender I'd look to the Eastbay style.
  3. 84far, Jan 6, 2011
    #3
    84far

    84far Senior Member

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    I think it also depends on how long the average stay on the water is...? If it's more about the day cruise, or an overnight stay then the Eastbay should be the go. Getting to the destination quicker should be the key.

    Generally at anchor or at say cruise speed a V shape hull will have what’s called a snap roll (the roll will have a jerk like feel). The displacement should be more of a clean roll.

    And general rule of thumb – sharper the entry (front of the boat), better the ride ;). And to go on, you want a decent V to about the midships, and then for it to flatten off towards the stern... say around 12-14deg deadrise. I think anything up around the 20+deg, boats start to play up going with the breeze.

    You might want to also consider whether you want a boat with a chine/spray chine. Usually at anchor this type of boat can be a little hard on the ears when you’re trying to get some sleep, most of the time it’s the fibreglass/glassfibre hulls ;). Cheers

    Far
  4. TimL, Jan 25, 2011
    #4
    TimL

    TimL New Member

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    more info

    Well, as my wife and I won't be retiring anytime soon - most of our trips are long weekends (3 to 4 days) and once a year we try and get out for a long week. Our current boat (nordic tug) is a semi displacement hard chined boat with a spray rail, so we have the quicker/snappy roll and the noisy spray rail. I would assume the deeper vee would reduce the snappy roll somewhat as that hard chine isn't as pronounced (is this wrong).

    I would assume a deep vee (eastbay) would be at least as stable as our tug in an anchorage. My thoughts for what we would want in a boat - quiet running (around 70 db or less at cruise 10 - 15 knots), ability to go a little faster when time is short, good seakeeping in 4 to 5 foot seas (when the weather picks up in the san juan islands), good handling around docks, and good ergonomics with access inside and outside the boat. I figure with the eastbay style, the fuel economy won't be that bad as we would probably cruise around 15 to 18 knots most of the time (we cruise at 9 knots on our tug). This cruise speed would either get us to our destination twice as fast or extend our range in the time allowed.

    We just don't want to end up making a mistake. My wife loves the kadey krogens but they are slow and our range vs time would be the same as now. I love the kadey krogens ability to handle rough weather, but in reality, if the weather is this bad, we probably would not be out in it. I think the eastbay would be more of a proper fit to our needs and something like the eastbay 46 sx would give us more room, good seakeeping, and allow us to open up our range or give us more time enjoying the anchorage when we arrive.

    I'm rambling a bit, but I'm sure many of you have had a similar dilema. Next question is - go with the 46 SX with the zues drives or 45 SX with conventional drives??
  5. NYCAP123, Jan 25, 2011
    #5
    NYCAP123

    NYCAP123 Senior Member

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    The Nordic is more of a bay boat. It's biggest draw is the tug nostalgia. Good boats though. I think you'll be very happy with an Eastbay for all of your (correct) assumptions and more. They're fine boats. I'd personally go with the Zeus. It's a complex piece of machinery, but the results are so worth it, from the fuel economy to the increased speed and the great handling, and no need for thrusters. My experience is on IPS more than Zeus, but they're pretty much the same in these respects. The 'pods' are definitely the way of the future. Not only will you enjoy them today, but they'll make the boat so much more attractive at resale. Good luck. BTW, although I personally love the Kadies, they're more for serious long distance cruising than it sound's like you need right now.
  6. Capt J, Jan 25, 2011
    #6
    Capt J

    Capt J Senior Member

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    I second this. However if you're not going to do a LOT of travel or hours, the conventional drives up front cost and maintanence cost will probably be cheaper in the long run for you, at the expense of maneuverability. But if you have no problems docking and maneuvering the Nordic with a single engine you should be fine with twin conventional engines in the Eastbay. However there are other choices in addition to the EastBay. The Eastbay has a lot of outdoorsy area. The Bridge Area, the Cockpit area, etc, but it's a little small on the inside (living space) in comparision to others in it's size range.
  7. TimL, Jan 26, 2011
    #7
    TimL

    TimL New Member

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    Thanks

    Thank all of you for responding. This helps confirm my thoughts.