Dan-O's first boat build. Small 8' Solar/Electric Cat!

Discussion in 'Boat Design' started by ElectroDanO, Sep 13, 2019.

  1. ElectroDanO
    Joined: Jul 2019
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    Location: Smyrna TN

    ElectroDanO Junior Member

    Hello everyone! First post but, long time lurker. Thanks for this awesome forum. So much great info on here! I'm ready to jump in and give it a shot!

    I've been a boat guy for a while now and currently have a '77 DiMarco jet boat that I'm in the middle of rebuilding. I missed being on the water so, I picked up a little 8'x5' paddle boat just to get us out there but, I couldn't leave it alone after I saw how well it worked. I added a trolling motor, solar setup, and other goodies. I've really had fun playing with this thing! I want to build a nicer hull for this project and take it to the next level. I haven't been able to find any plans that are exactly what I'm looking for but, this is fairly close to what I had in mind. L'il Nip Plans https://www.duckworks.com/product-p/mg-lilnip-id.htm This is the first time I've tried anything like this so, I'd like to stay at 8' on my first attempt to keep it cheap and easy. I'm not expecting perfection, I just want to learn on this one. I'm experienced in fiberglass and wood working so, I have that going for me. I'll post pictures of the progress. Please watch me and make sure I don't get too far off track!

    Here's a picture of the paddle boat. It's worked out very well and I don't want to stray too far from this basic design. Again, thank you!

    [​IMG]
     
  2. ElectroDanO
    Joined: Jul 2019
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    Location: Smyrna TN

    ElectroDanO Junior Member

    Been doing a TON of reading and have decided to stretch it out to 10 feet and narrow the hulls a little. I know it's not going to be anything super fast but, I do want to shoot for a little more speed. I'm still waiting on my 1/8" luan sheets to show up. That stuff has proven tough to get around here!

    Things I want out of the new hull:
    Fit on my 4x8 trailer(I can go wider than 4')
    400+lb capacity, room for two people, a dog and camping supplies.
    Strong and stable. I(155lbs) like to go for a swim and pull myself back in without flipping the boat.
    Worthy of power upgrades for more speed.
    Increase in speed over my current setup(3.6 MPH). Should be easy to beat!

    I played with DELFTship(I have no business messing with this) and at least came up with a very rough draft of what I'm thinking on the hulls. Flat bottom, no rocker, 10' long, 16" tall, 12-14" wide at the beam and 8-10" wide on the bottoms narrowing at the rear with a transom. Again, I know I'm not building a race boat but, I do want it to go faster with more power, more prop, ect. 5 MPH top speed would be amazing but, I would like it to be capable of 8-10 MPH if that's possible. Am I on the right track???
    [​IMG]
     
  3. Deering
    Joined: Feb 2005
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    Location: Juneau, Alaska

    Deering Senior Member

    Sounds like a fun project. And I think you are taking the right approach by not investing too much into a first boat. Since you’ll be running in displacement mode you’ll want to eliminate the flat submerged transom. That’s more suitable for a planing hull. Look at some canoes or rowing hulls for inspiration. Keep in mind that skinny hulls will be more sensitive to longitudinal loading for trim, so think carefully about where bodies and batteries will be located. If possible, delay final placement as long as possible so perhaps you can do some trial placements before locking in on locations. Having seats that you can reposition after it’s built will give you more flexibility in case you decide to get an additional battery or another pooch. Keeping the hulls as full as possible towards the ends will reduce trim sensitivity too.

    5 mph seems entirely plausible. 8 to 10, not likely given the displacement to length ratio. But I’m sure more knowledgeable designers can advise on that more competently than I.
     
  4. ElectroDanO
    Joined: Jul 2019
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    Location: Smyrna TN

    ElectroDanO Junior Member

    Thanks for the reply Deering! I had to go back and refresh on hull speed and a few other things. You're right, 5 MPH is probably going to be max, and I'd be absolutely thrilled with that. Heck, anything over 3.6 MPH and I'll be happy. I'm realizing everything I've learned about V8 hot rod boats does NOT cross over to this project! Stay with me guys, I'm learning...

    I guess what I'm REALLY after is more efficiency at low speed/low watts and hopefully gain a little speed at WOT as a side effect. I've already read the "Efficient electric boat" thread and upgraded my trolling motor with amazing results. The coolest part of this project to me is, being able to cruise all day(with sun) and still have a full battery when the sun goes down. In order for that to happen with the paddle boat, I have to keep speed under 2.5 MPH. That's the number I'm really looking to improve on...

    So, ditch the transoms and go double-ender? I'd love to do that on looks alone! I was just thinking transoms for more displacement but, I should easily be able to balance this thing wherever it needs to be. Nothing will be "locked in" until it's right. I just don't want it to draft too low the first time I get in it...:eek:

    Talk to me, I'm listening! I haven't started building yet and nothing's off the table. I will say, I'm excited to get to work!!!
     
  5. HJS
    Joined: Nov 2008
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    Location: 59 45 51 N 019 02 15 E

    HJS Member

    Attached Files:

  6. alan craig
    Joined: Jul 2012
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    Location: s.e. england

    alan craig Senior Member

    How long can you go on your trailer? I would say your ideal set up is a ready made catamaran 14ft to 16 ft. You would have to make it demountable to fit the trailer but that might be quicker than making two hulls.
    I have made a boat, an electric outboard and controller and a solar roof and have finally been trying it out. My conclusions are that a cat would be better for solar than my 14ft rowing skiff because 1)the dog hates it due to instability 2) 1 of the 3 panels has to be on the bow because of reduced stability with it mounted as a roof panel 3)it takes a while to assemble the roof at the ramp as I can't just fold it up or down. And I wouldn't want to pull myself in over the side after a swim.
     
  7. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

  8. ElectroDanO
    Joined: Jul 2019
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    Location: Smyrna TN

    ElectroDanO Junior Member

    Thanks guys! I couldn't sleep thinking about this stuff!

    Ha, this thing keeps getting longer by the day! I knew this would happen. I did some measuring last night and I could MAYBE stretch it out to 12 feet but, at that point, it's really going to take up a lot of space and be tough to move around. Let's try to keep this first attempt small and simple as possible. It will be kept inside(my house) and I'm just about out of room as it is. I should have more room for version 2.0 down the road.

    I looked into hacking up a Hobie cat a few months ago. I'm sure something like that would work good performance wise but, they're just too big, unattractive and I don't want to have to put my boat together at the ramp every time I go out for a quick ride. Everything's a compromise isn't it?

    Thanks for the link portacruise. I haven't seen that one yet. I've been getting stuff together for brushless/lithium power! So exciting!
     
  9. Deering
    Joined: Feb 2005
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    Location: Juneau, Alaska

    Deering Senior Member

    If you planned for it ahead of time it might be feasible to construct the hulls to accommodate future lengthening by adding an extension length in the middle of each hull. Think of the 10’ hull being built in two 5’ sections with a flange bolting them together. At some later point you could insert another x ft section between them. This would include both max speed and payload. Doing this at the center would be easiest since the hulls will likely be symmetrical there.
     
  10. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Dan O you appear to be committed to the catamaran type? Why? If you want the best performance with limited power, you need to calculate the wetted surfaces of your boat. Something like the Keyhaven design will almost surely perform better, with a small propulsive unit, than a small cat. The boat shown by HJS is an ideal candidate, Easier to build and probably lighter than a cat of equivalent displacement. Note that the Keyhaven has a "trapeze bottom" which is the second best configuration in terms of wetted surface. Flat bottoms are the worst in terms of wetted surface and they also create power robbing turbulence at the chines. Chine turbulence is somewhat mitigated by the bevel chined "trapeze".

    If you mean to design your own boat then do give some consideration to those factors.
     
  11. W9GFO
    Joined: Dec 2014
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    W9GFO Senior Member

    I am not disagreeing, but would like to point out that the Rick Willoughby style of flat bottom human powered stabilized monohulls has been shown to be very efficient. Having a flat bottom allows for a greater beam to length ratio for a given draft, displacement and length of hull; and reportedly provides some beneficial pitch dampening. I think the negative aspects of the hard chine diminish with greater beam to length ratio.
     
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  12. W9GFO
    Joined: Dec 2014
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    Location: Olalla, WA

    W9GFO Senior Member

    I have been using Free!Ship Plus for quite a while now. I have downloaded and tried DelftShip a couple times, and while I cannot remember the specific reasons* I always go back to Free!Ship. I think Free!Ship is the predecessor to DelftShip, it is very similar and Free!Ship comes with a good manual.
    FREE!ship https://sourceforge.net/projects/freeship/
    I also found that using Wine Bottler I am able to run Free!Ship on my Mac just as if it were any other Mac program.

    * I think the main reason is that the free version of DelftShip does not allow exporting developed plates - being a non-professional, that is a deal breaker for me.
     
  13. ElectroDanO
    Joined: Jul 2019
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    Location: Smyrna TN

    ElectroDanO Junior Member

    Thank you so much for the replies! I don't have anyone around here to talk to about this stuff and I sure don't need to wing it by myself...

    Deering: That's a good thought but, I've pretty much come around to the idea of stretching it out to 12' now. I'll have enough wood to pull it off. Great, just what I need...:D

    messabout: Why a cat? Stability and good looks 100%. I should add that I run in a good sized lake with some serous wake makers. I've put a lot of miles on this little paddle boat and it has been absolutely prefect, even in really rough water. I CAN'T lose that. I know I'm giving up a lot in the speed department vs a slick mono but, I've been out there with my friends in their canoes and small monos. I'm enjoying myself 10 times more.:cool:

    W9GFO: My flat bottom/no rocker idea is just to keep things easy and simple on my first build and keep stability as high as possible. I'm scared to death of doing all of this work and it being tippy or sitting too low in the water. This is a HUGE learning experience for me. If it turns out kinda decent, I will gladly build another one with a lot more effort and nicer supplies. Hey, I have to learn some of what NOT to do first right?:confused: Thanks for that link also. I will check it out for sure!

    Here's a pic of something similar to what I have in mind. How cool would that be as a double-ender and with a nicer deck?
    [​IMG]
    [​IMG]
     

  14. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

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