Moderate Speed... Any Weather

Discussion in 'Boat Design' started by ALowell, Mar 22, 2007.

  1. charmc
    Joined: Jan 2007
    Posts: 2,391
    Likes: 78, Points: 0, Legacy Rep: 840
    Location: FL, USA

    charmc Senior Member

    Gilbert,

    I believe your speed estimate. The Uniflite 31 hull was well known as a great seakeeper. I once saw a 50' cruiser attempt to go out through Manasquan Inlet, NJ into the Atlantic during a pretty nasty noreaster with steep 8-10' seas. They were banged about pretty badly, turned around, and barely made it back in, after sustaining damage, although they never went more than 8 - 10 knots. About 10 minutes later, a Uniflite 31 sportfisherman made the same run and disappeared into the distance, on plane at around 15 - 17 knots. Obviously, operator skill was a big part of the difference, but the Uniflite hull had no problem maintaining a good speed in very heavy seas.
     
  2. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 111, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Displacement boats usually need extra stability (flopper stoppers or active fins) and 100 to 200% of the normal power to progress in heavy going.

    Many just dont have the reserve power.

    Semi and full plaining boats will gain stability while running fast , so do better in heavy going , IF the ride isn't too rough for the operators to stay intact.

    FF
     
  3. RonW
    Joined: Mar 2007
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 29
    Location: Ohio

    RonW Junior Member

    Allowell- your thread took a turn and got even more interesting.
    You started off with a power cat at 3 times the speed. Appearantly you have decided the rough water quality of the boat became more important then the speed factor.
    For a minute I thought you posted pictures and diagrams of the bartender.
    That is a neat little boat, the righting arm is great, and fuel economy is as good as it gets. So are you or will you be happy with the greatly reduced speed, and does the boat have enough room and or is the layout to your satisfaction.It is interesting as to how people start in one direction and as they really refine their most important features, how they end up changing, and sometimes dramatically. I bet that little boat can take some waves that no one in their right mind would be out in.
     
  4. ALowell
    Joined: Mar 2007
    Posts: 70
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: Northeast, USA

    ALowell Junior Member

    How do you know what the righting arm is, or are you referring to the Bartender?

    You are right that I have significantly changed my priorities. However, I've known about this boat for a few years and my preferences seem to sway between planing and hull-speed pretty frequently. I guess I'll just end up buying whichever I happen to be interested in at the time of purchase, because I don't seem to be completely satisfied with either.

    My real concern with this boat is that at 6 knots I won't even be over the horizon after an hour of travel, whereas at 15 knots I'd be at my destination by then! Do people in hull-speed boats have to wear straight jackets?


    ~ ALowell
     
  5. kach22i
    Joined: Feb 2005
    Posts: 2,418
    Likes: 111, Points: 63, Legacy Rep: 1222
    Location: Michigan

    kach22i Architect

    I've been doing some thinking on this in a related topic, hovercraft and cushion height. You can come off cushion if a wave or wake is large enough to come up underneath you and the crest lifts the bottom of the hull. The hovercraft tends to follow the wave down into the trough bottom and gets overtaken in displacement mode.

    The only cure is a larger hovercraft with higher cushion height. It would be nice if the bottom of the hull could be shaped to deflect as in the blue catamaran illustration on page 5 by "kerosene".

    http://www.drbeach.org/drbeach/pulse.htm
    [​IMG]

    http://www.globalsecurity.org/military/systems/ship/beginner.htm
    [​IMG]
     
  6. ALowell
    Joined: Mar 2007
    Posts: 70
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: Northeast, USA

    ALowell Junior Member

    Aren't hovercraft pretty uncomfortable in waves due to heaving? I considered an SES as a solution to my design problem but I abandoned the idea because of what I read about heaving. I still wonder if this could be solved with expandable air chambers that would temporarily expand to take up excess pressure when encountering a wave. High-rate springs would then collapse the chambers when the wave passed thus preparing for the next wave pressure spike. If that doesn't make sense maybe I need to draw a picture.... Anyway, it's much more R&D than I can tackle at this point in my life.

    ~ ALowell
     
  7. RonW
    Joined: Mar 2007
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 29
    Location: Ohio

    RonW Junior Member

    At 6 knots it will take 3 hours before you are over the horizon, that makes for being able to wave good-bye for a loooong timeeee....

    I think as far as a full dissplacement hull, you have to always be in very rough water, or be very highly intelligent, as to always contemplating technical thoughts for hours, or just too stupid to ever think about anything, to be able to stand the high speed effect of 6 knots in a power boat.

    That is why I have such a interest in seeing the revival of the old time launches, or more of the semi- planning hulls, that give you a little of both worlds. The boat rides smooth in choppy water, but yet still cruisers at the mid teens or above according to size.
    If you want to build a wooden boat, there are some great old time designs on the atkin site.
     
  8. ALowell
    Joined: Mar 2007
    Posts: 70
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: Northeast, USA

    ALowell Junior Member

    I don't love the Atkin designs because of the complex shapes involved in creating the propeller tunnels. This would greatly complicate building and would definitely require building molds which is something I want to avoid. Also, none of them look like they are prepared to take on truly nasty weather, though I might be wrong.

    What I keep looking for is one of the launches that people have mentioned built by Hereshoff. I can't seem to find anything useful online.

    ~ ALowell
     
  9. RonW
    Joined: Mar 2007
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 29
    Location: Ohio

    RonW Junior Member

    If you are disscounting the atkin designs due to the prop tunnels, those are only on the sea bright skiffs, he has tons of other plans.
    Look at the inboard utilities and inboard cruisers.

    http://www.boat-links.com/Atkinco/

    There are plenty of old time semi-planning hull designs.
    Literally dozens to pick from, and a lot of these can be altrered as to layout and some can even be changed to outboards.
     
  10. RonW
    Joined: Mar 2007
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 29
    Location: Ohio

    RonW Junior Member

    Here is a launch, I even have the plans for it.
    Then there is the ketwomoke, utility, both rough water boats, no prop tunnells.

    http://www.boat-links.com/Atkinco/Utilities/Pennant.html

    Actually the ketewomoke and utility is nothing more then a larger version of richard pulsifer's hampton.
     
  11. kach22i
    Joined: Feb 2005
    Posts: 2,418
    Likes: 111, Points: 63, Legacy Rep: 1222
    Location: Michigan

    kach22i Architect

    You might find this thread interesting, I sure did, Look for posts by BMcF.

    Link:
    http://www.boatdesign.net/forums/showthrea...6210&page=2

    Sample regarding SES (and hovercraft):
    BMcF is Bill McFann of Island Engineering.
    http://www.islandengineering.com/
     
  12. Geoh
    Joined: Jan 2007
    Posts: 53
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: Arizona

    Geoh Junior Member

    Allweather boat

    Hello ALowell

    I just bought the allweather boat 1982 model. I just finished painting the boat. I will have it in the water this week..Putting it in lake Mohave here in AZ Then if no mechanical problems trailering it to the Sea of Cortez.
    There were only 32 made and none since the late 90s

    George
     
  13. longliner45
    Joined: Dec 2005
    Posts: 1,629
    Likes: 73, Points: 0, Legacy Rep: 505
    Location: Ohio

    longliner45 Senior Member

    hey guys look at this and tell me what you think,,(powerand motoryacht,com,),,,,,,,,,,,,look up boat test31jcboat,,,,and read the specks ,,,,thanks ,,,,,,,,longliner,the boat featured is called the boxer
     
  14. Geoh
    Joined: Jan 2007
    Posts: 53
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: Arizona

    Geoh Junior Member

    allweather

    testing attachments
    Less than a mile from the Colorado river, in the old days i cudda just floated on down stream to mexico...

    George
     

    Attached Files:


  15. longliner45
    Joined: Dec 2005
    Posts: 1,629
    Likes: 73, Points: 0, Legacy Rep: 505
    Location: Ohio

    longliner45 Senior Member

    nice lines man
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.