Function of design

Discussion in 'Boat Design' started by Salmoneyes, Nov 5, 2018.

  1. Salmoneyes
    Joined: Sep 2018
    Posts: 79
    Likes: 1, Points: 8
    Location: Southern Oregon

    Salmoneyes Junior Member

    My searching came up with that as well. In fact a very informative (for me) article about transom design exists and although it is a bit of a read, I did learn a lot. Unfortunately it only provided a paragraph to the design I am asking about and it more or less says what philSweet said in the begining.

    https://www.glen-l.com/phpBB2/viewtopic.php?t=27907

    Transoms.jpg
     
  2. Salmoneyes
    Joined: Sep 2018
    Posts: 79
    Likes: 1, Points: 8
    Location: Southern Oregon

    Salmoneyes Junior Member

    You seem to have some personal experience with this transom design.. Please feel free to share some photos, and or the specifications plus your full opinion...
     
  3. SamSam
    Joined: Feb 2005
    Posts: 3,811
    Likes: 147, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    I've always thought of squat boards as being extensions of the hull bottom, usually added as a remedy, which were just permanent, un-adjustable trim tabs.

    A lot of times those hull extensions, as in the op, are used as bait wells. Sometimes they won't have pumps, but will have holes in the sides and back for water exchange. They still work as anti- squat, trim tab devises while running, but holes have to be drilled high enough or provisions have to be made to scoop water into them while running so they don't drain out.

    A friend had one of those "Gheenoe" boats with apparently too big a motor. He was out duck hunting and put it in reverse and the boat just drilled itself under water. He was surprised how fast it all happened too. Took him and his buddy 6 hours to slog out of the marshes.
     
  4. Salmoneyes
    Joined: Sep 2018
    Posts: 79
    Likes: 1, Points: 8
    Location: Southern Oregon

    Salmoneyes Junior Member

    Interesting idea to use for bait, but clearly it provides "space" that can bill utilized...
    After reading that transom design tutorial, I feel I understand how the genesis of adding "something" to the transom, allows for more modifications, more additions, until you eventually get back to where you started only it is now a longer boat....

    I am very interested in the claim that it improves its ability to be towed. This is a benefit I can utilize.

    I also like the idea of moving that weight forward, in relation to the hulls LWL. Im sure there are negatives to that, but for my use, it would benefit. Hopefully someone will chime in and provide me more understanding, so I can properly weigh those benefits...
     
  5. philSweet
    Joined: May 2008
    Posts: 2,122
    Likes: 114, Points: 63, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

  6. Salmoneyes
    Joined: Sep 2018
    Posts: 79
    Likes: 1, Points: 8
    Location: Southern Oregon

    Salmoneyes Junior Member

    I like it.. I have looked very serious at that design. ( I have a Livingston) and there is a lot about those that works for my project. I sent for study plans on this

    Boat Designs and Kits | Spirited News https://spiriteddesigns.com.au/news/ripple_tender?category=1
     
  7. jorgepease
    Joined: Feb 2012
    Posts: 1,614
    Likes: 45, Points: 48, Legacy Rep: 75
    Location: Florida

    jorgepease Senior Member

    Besides all mentioned, very many skinny water flats boats have sponsons. Among other things they serve as a step for waders returning from fishing, keep the stern from digging in when popping out of a hole, slower planing speeds, help contain the raised water level along with a pocket tunnel. You have to make sure to rake them or they can keep the bow down and don't let them be too long or it will mess with your steering. I think the use is limited on the boat you show.
     
  8. Salmoneyes
    Joined: Sep 2018
    Posts: 79
    Likes: 1, Points: 8
    Location: Southern Oregon

    Salmoneyes Junior Member

    Finally,, a name to go with it... Sponsons... I looked it up... Thank You

    "help contain the raised water level along with a pocket tunnel"
    Need an a bit of explanation on this

    "keep the stern from digging in when popping out of a hole,"
    This is a good thing for my project

    "slower planing speeds"
    To be clear,,, are you saying
    the boat goes slower once planed (not a deal breaker for me)
    or
    the boat planes at a slower speed (this is a big benefit to me)

    "You have to make sure to rake them or they can keep the bow down"
    I will assume this is like a trim tab effect, if the "sponson" has a downward angle in relation to the hull, it would push the bow down.
    This is interesting, but In my case, I am considering trim tabs since this boat will be what Im calling a "truck", as opposed to a "taxi" unless that angle can be determined to work best in light or heavy mode.

    "too long or it will mess with your steering".
    This would not be desired, so figuring out that relationship will need to be addressed.

    These are all great points, and I appreciate this response. Anytime I can solve a problem I don't know exists yet, I am that much farther ahead...
     
  9. jorgepease
    Joined: Feb 2012
    Posts: 1,614
    Likes: 45, Points: 48, Legacy Rep: 75
    Location: Florida

    jorgepease Senior Member

    The boat planes at a slower speed (this is a big benefit to me) - yes, the boat can stay up on plane at slower speeds, this is what I mean. If your boat is intended to plane then rake the sponsons up the same °angle you want the bow to come up but I wouldn't angle them down. I have seen transoms inset 24 inches + with no problems, more if also using a jack plate. If the boat is to have a tunnel then the shortest jack plate works best.

    When used to increase the ability to run shallow, a small tunnel the last 4-5 feet of the boat lifts water which shoots up into the area between the sponsons. On my old boat, for example, using a heavy cupped prop, I have run in as little as 2" of water. The prop is raised above bottom of boat between sponsons. It doesn't sound like that is what you are going for.
     
  10. Salmoneyes
    Joined: Sep 2018
    Posts: 79
    Likes: 1, Points: 8
    Location: Southern Oregon

    Salmoneyes Junior Member

    Thank you for the clarification...

    Running shallow would be a benefit, not necessarily a requirement...

    I spent time in Belize where we ran up these little creeks to get fresh water. Hadn't thought about that but it is a plus to be able to do that, which hauling weight is the main criteria...
     
  11. jorgepease
    Joined: Feb 2012
    Posts: 1,614
    Likes: 45, Points: 48, Legacy Rep: 75
    Location: Florida

    jorgepease Senior Member

    if hauling weight, running skinny are important, then go with a flat hull.

    The one I built, shown, was amazingly stable because it had an almost 8' beam, low to the water so easy to load stuff, and super shallow running. The more weight you put on it the better it runs lol.

    I have crossed a hard rock bottom with 9 people aboard and barely any water (less than 3 inches) at slow speed because the water pressurizes, flattening and lifting the boat up. It's really cool feeling, you go slow so as not to starve the tunnel of water which is good anyway because it's dangerous.

    The big flat bottom with a tunnel is a lot of drag so if you want a fast boat it's not for you. The most important part is to get a good cupped prop from one of a few people that really know how to do it and they are all in Texas LOL Baumann Marine are the guys that did mine.
     

    Attached Files:

  12. Salmoneyes
    Joined: Sep 2018
    Posts: 79
    Likes: 1, Points: 8
    Location: Southern Oregon

    Salmoneyes Junior Member

    I really like this. I would love to be able to strap that to the deck of our motorsailer and have all that usable deck space on the tender. Plus mine hangs over the stern a bit so actually gives me more deck length. I’d love some info on her numbers.
     

  13. Squidly-Diddly
    Joined: Sep 2007
    Posts: 1,296
    Likes: 31, Points: 48, Legacy Rep: 304
    Location: SF bay

    Squidly-Diddly Senior Member

    that looks comfy and ergo-metric especially for sitting on and as others have said will help float the heavy motor, and no doubt make the whole boat feel more stable.....but....

    consider these brackets that do the opposite. Main advantage seems to be letting the hull and prop do their very diff tasks better by a bit of separation.The Benefits of a Bracket on Your Outboard-Powered Boat https://www.powerandmotoryacht.com/maintenance/the-benefits-of-a-bracket-on-your-boat

    But I guess the extensions (I'm thinking they are extensions, not "moving transom forward") will be above water when planing so it would be just normal transom.

    Maybe make hybrid float/water ballast extensions that partly fill with water ballast at rest then eject it when hull tips to start planing, similar to RIB rescue boats.
     
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.