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Plumb Bows

Discussion in 'General Yachting Discussion' started by PacBlue, Oct 24, 2019.

  1. PacBlue

    PacBlue Senior Member

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    I have always wondered about the re-appearance of Plumb (vertical) Bows in Small Yacht Design after they were abandoned years ago. Is it just a designer trend, to be different, or does it have a functional benefit?

    I really wonder how all these new 30 - 60 Coupe/Expresses do in any seaway as you typically only see promo videos in underway smooth water.

    Happened to catch some video at Haulover Inlet in Miami (just google it) and confirmed what I expected - the modern Plumb Bow Express/Planning boat was extremely wet with water gushing all over the place. Wipers working furiously to get any view forward. Streams of green water cascading over the hardtop into the cockpit.

    Why would anyone commit to this design knowing their poor head sea capabilities and if they do not have a smartly designed cut-away forefoot, an equally bad tendency to trip or broach in steep following seas?

    Just to look different? Dockside queens?
  2. Capt J

    Capt J Senior Member

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    Well, people mostly buy a yacht based on it's appearance. Then the other situation is, how do most yacht/boat buyers compare the boat they're buying to another boat. Most have not ridden on many boats/yachts. SO how do they know if the ride on this boat/yacht is much better than that boat/yacht. They have nothing to compare it to. They don't know if a boat should be wet or not. I have the luxury and run 100-150 different boats/yachts a year......so I have a library of experiences to compare each boat to and from type to type. Very few owners and even Captains have this luxury.
  3. Beau

    Beau Senior Member

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    Some of the down eastr's seem to have somewhat of a plumb bow. Aren't they good sea boats?
  4. AMG

    AMG YF Moderator

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    My 80-footer is not so wet I think, here she is at around 27 knots in a moderate sea;

    Kevin likes this.
  5. PacBlue

    PacBlue Senior Member

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    Nice video, although those look to be fairly light to moderate seas. I have seen that you have a nice fine entry and a relatively narrow bow enhanced by the benefit of an 80 foot length. She cuts through the water nicely, have you been in bigger seas where you have to punch through larger swells?

    When looking at the current 30 - 60’ production boats that throw in a very comfortable fwd stateroom that creates a wide and full bow, plus the trend for more exterior living space on the forward deck, the forward sections seem to become bulky and full in lesser loa. These are the boats I am more focused on, wondering what the owners think?

    A downeast design is a bit of a different animal than what I am talking about - a planing hull with a plumb bow, hard chines, in the 30’ - 60’ range.
  6. AMG

    AMG YF Moderator

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    Our experience is that we let the Humphree interceptors trim the bow down in bigger seas where it cuts through instead of bumping, and the spray is still not too bad. It is all about finding the right equation of all angles, weight, COG, length/beam and not least the speed, but I think the plumb bow is beneficial on this design.
  7. PacBlue

    PacBlue Senior Member

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    I like the engineering captured in your response, that 80 has really nice angles.
  8. Beau

    Beau Senior Member

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    I figured so after seeing that video. There is very little radius before the transition to what I'll call the fore keel?
  9. AMG

    AMG YF Moderator

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    I don't know exactly what you mean, but here is the waterline at rest on this hull, so it is pretty sharp...

    Skärmavbild 2019-10-25 kl. 02.18.15.png
  10. Beau

    Beau Senior Member

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    I
    You guys are way more advanced than I so my vocabulary is limited. But looking from the side on the video, the bow comes down perpendicular to the water very straight then transitions to the fore to aft portion of the boat (the fore keel?) with a very tight radius. The down-easter's as I now compare them to your the video, have more of that sweeping transition/radius of a traditional sport fisher even if the bow is a little more perpendicular. Ignore my comments because my first comment really have very little relevancy as I see from the video.
  11. RB480

    RB480 Senior Member

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    Being involved with a mid 50' plumb bow express, I can tell you from experience that its extremely frustrating in a head sea as the boat gets totally soaked.
  12. captaintilt

    captaintilt Senior Member

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    I've been fortunate to run quite a few plumb bow boats this year, and Im slowly beginning to be a fan of them, but follow on AMG's comments in that you have to really play with the trim angle, speed when running into a head sea. I actually ran a 70' Plumb Bow in a 2 ' head sea this spring that actually rode a little wetter and harder than a 50' Plumb Bow that I had to plow across Lake Erie from the Welland down to Erie in 4 to 5's to get into the lee. That 50' handled it much better with the interceptors buried than the 70' did with a 2 ' head sea.
  13. Prospective

    Prospective Senior Member

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    Good friend owns a Fjord 40. To the points above... one of the reasons he picked the boat is the aesthetics, reminiscent of a racing sailboat. And, based on his description of his ride is seas I was also in in my Ocean, sounds like the boat is pretty wet.
  14. PacBlue

    PacBlue Senior Member

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    How do they handle in a following sea with a decent swell?
  15. captaintilt

    captaintilt Senior Member

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    The 50' plumb bow that I've ran quite a bit did very well in a following sea and tracked nicely. I had a 4' following swell from Atlantic City to Sandy Hook a few weeks ago and was still able to run 24 knots pretty easily
  16. PacBlue

    PacBlue Senior Member

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    I was thinking more when the seas kick up quite a bit and you are reduced to displacement (not planning) speeds?
  17. cleanslate

    cleanslate Senior Member

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    Wow! Very nice boat.
    I see some of the older designs in the Plumb bow / hull design , going way back to Elco, Matthews etc pre 1950 ... Which I think is/was awesome .
    Yours being of modern times , design and construction . But the narrow beam Elcos , Matthews cut through the water so well. Like your boat .
    No pounding .
    It's really impressive.
  18. cleanslate

    cleanslate Senior Member

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    Aren't all boats , and Captains , reduced to displacement speeds in heavy weather, unless you want to start busting up bulk heads and such...
  19. Capt Ralph

    Capt Ralph Senior Member

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    I think we are confusing the newer plumb bows that run with the stem out & above the water and a planing hull is under the ship with the stem of the older displacement hulls that were always well in the water.

    Either way, I'll always lean to a lifting bow. I've stuffed enough junk into inlet waves.
  20. Capt J

    Capt J Senior Member

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    NO, it depends on how heavy the seas are, the spacing of the seas and the angle. I've had a lot of seas where I could run cruise speed or 28 knots in a 62' with seas on the beam or stern....but if the seas are on the bow slowing down to 22-24 knots or more...….in say 4-6'. Generally a planning hull runs best in a heavy sea when it is just barely on plane......20-24 knots in a lot of boats...…..Of course if things get REALLY big, you're slowing down to hull speed or somewhere between hull speed and on plane..........unless you're in a 2000's era Bertram, it takes a hell of a lot to break bulkheads. Your more concerned about breaking things on the interior and getting cabinet doors and things like that out of adjustment.