Flyfishing kick boat cat

Discussion in 'Multihulls' started by Brian Fanner, Jul 6, 2020.

  1. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    Hi all.

    I'm working on this flyfishing kickboat project. Designed in freeship. I've made this little model. Hulls would be 2m long at full size. It will have decks...Stitch and glue glass sheathed with hatches for storage. Displacement at 200mm is around 100kg.

    https://photos.app.goo.gl/LZWMP6uU3SqSjnQN9

    Hoping for any random input especially surrounding the details of how to do hatches and the seat frame and connecting the hulls and central frame. My thinking is to build strong PVC pipes into the hulls that the frame can slide into apon which you can build the seat and possibly battery and trolling motor mount on the front. May also need some advice on other construction stuff as I build it.

    Thanks all.
     
  2. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    Ok seems the google photos link doesn't work... hmm
     
  3. bajansailor
    Joined: Oct 2007
    Posts: 998
    Likes: 266, Points: 63, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    Welcome to the Forum Brian.

    Re the google photos, can you perhaps attach them as simple jpg's using the 'upload a file' icon below?
     
  4. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    20200627_161253.jpg 20200627_160939.jpg

    Thanks! Didn't see that option before.

    I guess my main area of concern right now is should the hatches be cut into the decks on the cnc before assembly... should I just buy some round boat hatches and use those... or perhaps the midships area should just be completely open for storage of such things like a cooler box, landing net etc. I was considering a built in cooler box but in second thoughts a small removable cooler box might be easier to keep clean, and keep the boat weight down.

    Any thoughts would be appreciated
     
  5. bajansailor
    Joined: Oct 2007
    Posts: 998
    Likes: 266, Points: 63, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    I guess that you could leave the two midship sections in the hulls open, if you deck over the fore and aft sections for positive buoyancy.
    Rather than building hatches, the round plastic boat hatches that screw in would be fine for access to these compartments
    Will you have a small bridgedeck between the two beams to sit on?
    How long is the model in the photos above?
    Do you want the transverse beams to be laminated to the hulls, or will you want to be able to disassemble the hulls for transporting?
     
  6. upchurchmr
    Joined: Feb 2011
    Posts: 2,999
    Likes: 139, Points: 63, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Narrower hulls will be easier to kick.
    As this will be a slow boat, double ended is easier to define, and has low resistance.
    It would be easy to develop shapes to make this out of strip planked cedar.
    Round bottom will be easier to kick, but if you try this, be sure the bow and stern are about 1 to 1.5" sunk into the water, or the boat will be difficult to keep going straight.
    I built an 11' x 4' catamaran row boat which weighed 50#. That is where my recommendations came from. (lots of hard learned lessons - I.E.: had to rebuild several times until I got it right.)
    The width of the individual hull was 6". This supported 125# with a 4" freeboard (for my wife).

    Don't use PVC for your crossmembers, it bends too much.
    Go to a metal supply house and ask for "cutoffs" or "drops" which they will sell for a minimal $/#. Aluminum tube (pipe will be thicker than you need).

    Make the deck flat. Easier to build, and while fishing you will have a good place to place stuff.

    If you don't want to try strip planked round bottom, you could make a good boat with flat sides, flat deck, with a "flat" bottom that has a gentle curve in the bottom. It probably will have less wetted surface than the V shaped bottom you show (at least what I assume you have). You really won't need CNC unless you just want to do that.
    With either round bottom of "flat sided" ply you don't need interior bulkheads at 2 meter.

    Have you used a kick boat before? I would worry that your seat will be too high off the water to do an effective kick, with what I assume are the dimensions on what you show.

    Sounds like a great project. I'll be interested in how easy it is to turn while kicking. I've never used one myself.
    Also. If you can remove or flip up the seat so you can step in the middle of what you show above, it will be easy to carry the boat to water by grabbing the fore and aft crossbeams. If it is not too heavy.
     
    bajansailor likes this.
  7. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    Thanks for the ideas. Much appreciated!

    Yes I have spent many hundreds of hours kicking around in a belly boat with my butt in the freezing cold water. That's probably the main inspiration to do this. A faster boat that can't puncture and has me sitting clear of the water.

    Well the bottom is a shallow v with a fairly big rocker. My thinking was to keep the hulls a little wider and shorter and have the rocker quite pronounced for a balance of efficiency and maneuverability. I'm looking at a 5 inch draft at around 90kg loaded weight and hoping the boat will not be very heavy.

    The pvc wouldn't be for the frame. It's more a way to slide the hulls onto the frame. And yes definately must come apart for transport. So pvc pipes built into the hulls transversely and a steel/aluminium sort of H frame for the seat to go on. This frame can slide into the pvc sheaths in the hulls and just attached with a strap or something. My friend has a pisces predator kickboat with pontoons that has him probably 10 to 12 inches above the water. He gets around fine. But we agreed it's too high especially for fish handling in catch and release where it's better to unhook and release the fish without removing it from the water.

    I think with regards efficiency it's going to be a huge improvement on a blob shaped belly boat that you need to plough through the water but the efficiency thing isn't too critical. It's mostly a very slow speed operation. What I'm after is out the water with the bum but not too high. Easy to kick with reasonably decent tracking and good maneuverability.

    I don't think I'd need to access the front and rear sections but I guess some sort of pressure regulating plug would be good for traveling upcountry to allow pressure to balance. Otherwise they would probably pop right?

    Weight is a very big concern. The lighter the better. Anything that can be left off should be left off. The storage in the midships section will be ample... in fact luxury compared to what I am used to. The one on the left would primarily be a stripping basket for fly line and a rod holder and net storage. On the right would be cooler box and other clobber..

    The model is 480mm long 20200627_164121.jpg
    Here it is loaded with around equivalent of 120kg so I'm hoping to be somewhere between the unloaded hull and this.

    Final though on the hill design... they look pretty to my eye. I'm a fine artist by training so probably putting too much emphasis on aesthetics but I can't help it. I do think though that having the v bottom with rocker will be more easy to turn or rotate. This is very important in belly boat flyfishing because you might spot a fish rising and need to quickly turn the boat. Longer nartower flat bottomed hulls without rocker wouldn't turn very well would they?

    Thanks!
     
    bajansailor likes this.
  8. gonzo
    Joined: Aug 2002
    Posts: 14,338
    Likes: 619, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    A longer narrower boat will be harder to turn whether it is a vee or flat bottom. For the same length, beam and rocker, a flat bottom boat will turn easier.
     
  9. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    That makes a lot of sense gonzo. One reasoning for the V bottom I had thought about was to be able to run a strip of aluminium down the length on the bottom of the V to act as a protection when fishing over shallow areas and rocky bottoms. If it is totally flat then the whole bottom is going to be needing regular repairs to the paintwork etc. Also there is the weed factor. Often one needs to navigate trough and over weed beds and I'm imagining the V cutting through this more easily. I do think the whole nature of fishing from a kickboat is such a slow leisurely pursuit that the performance of the hulls won't be that critical. I really just need it to float, be stable and not be heavy! And the all important bum out the water!

    I have now changed the decks to be flat. This will make it much easier to strap them to a roof rack. and ditched the idea of built in cooler box in favour of just nice open storage on both sides. I can chuck in a commercial little cooler box. it'll make keeping things dry and clean in the hulls much easier and keep the weight down.

    If I make the bottoms flat I'll need to start again on the design process. But I am considering it or just a slightly more shallow v still..

    Thanks for your input!
     
  10. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    Just a thought.... if you consider it part sled part boat the V has appeal. Even carrying a loaded blow up bellyboat, which is pretty lightweight, is getting a little challenging especially at altitude! I could just drag this boat around if it has nice bottom skids so to speak. and I would then avoid the inevitable need for a beach dolly of some sort.
     
  11. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    T200 Thruster for ROVs, AUVs, and marine robotics https://bluerobotics.com/store/thrusters/t100-t200-thrusters/t200-thruster/

    These look like an interesting and not too pricey option for propulsion. Not going to happen initially but just looking around at options. Could it just point forward and then steer with the flippers? now if you have two, one on each side it could turn on a dime. Hmmm...

    Thinking of redesigning the hull a bit... more around how the seat frame attaches to the hull but also a shallowing of he V.

    I'm not sure if anyone can assist but if I design the panels in freeship, then insert those panels into fusion 360 firstly it comes out tiny... like a 2mm hull length. and then blowing them up on fusion 360 produces some drawings that fusion 360 does not like at all. Just moving and mirroring sketches in fusion using freeship drawings is crashing fusion badly. I possibly need to insert the panels into fusion 360 then convert the lines to splines perhaps? Not winning as it takes ages to lay out the stuff with fusion freezing all the time. I think its just moving too any little lines. I set frreship to lowest resolution as well so the panels are not nicely curved but made up of longish lines. its not ideal
     
  12. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    Searched quite a bit for the right size aluminium pipes that could fit together nicely from which to build a seat frame and have the hulls slide onto the seat frame. You would imagine this would be possible but it seems only if you order a massive qty of the stuff. But I have now happened upon an aluminium pool cleaning pole which is retractable. The outer pole is 32mm OD and inner is 28mm OD so the outer pole is at probably a 1.8mm wall min.. Plugging this into a tube calculator and it can support 220 lbs over a 26 inch seat frame. So I think that will be perfect. The weight would be spread between two poles each capable of supporting 220lbs
     
  13. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    OK... I have redesigned, and redesigned and them chucked it all and redesigned again lol.

    I think I have a better hull now. Double ender as suggested, with much a much flatter buoyancy curve. Still got a V bottom but way flatter. Should be way more stable longitudinally.

    Working on a model.

    Figured out the scaling from freeship to fusion.

    Just the freezing and crashing fusion out badly if I use high resolution on freeship is annoying!
     
  14. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    Ok! you guys win with the flat bottom. You just can't increase the displacement to an acceptable level at the 2m hull length with two chines and a V bottom. I have come up with a compromise incorporating a flat bottom and 2 chines. I got the displacement up to 60kg from 40 (times 2 for 2 hulls) at 120mm draft... and a much flatter buoyancy curve with much more buoyancy fore and aft. It will be a lot less pitchy right? And as I am around 75kg plus 5kg for gear snacks and beer plus who knows how much the boat will weigh.... I'm guessing 15kg or there about, total thumb suck. I'll be floating at around 100mm draft which is acceptable. at 200mm draft its 200kg displacement and that's a lot of fish and extra beer capacity.

    working on a new test model now
     

  15. Brian Fanner
    Joined: Jul 2020
    Posts: 15
    Likes: 1, Points: 3
    Location: Hopefield South Africa

    Brian Fanner Junior Member

    20200723_100546.jpg 20200723_100559.jpg

    Here is the newly modeled out hull. I think its better right? Flat bottom almost... shallower draft... more boyancy forward and aft and just in general. Better longitudinal stability.

    I didn't build 2 for the cat. Too much work. But I can see the panels will go together pretty easily.

    Quite a lot of rocker for maneuverability and stealth!

    The aft deck tapers off as with rod tip down it'll be less in the way when you fish at an angle to the boat.

    There will be decks. The front bulkhead will be further back. I cut the wrong one for the model...:rolleyes:... which is a good reason to build a model!
     

    Attached Files:

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.