Newbie wohooooo!!!! Need help!!!! 20' Flat bottom River boat

Discussion in 'Fiberglass and Composite Boat Building' started by riverboat_20, Apr 3, 2008.

  1. riverboat_20
    Joined: Apr 2008
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    Location: Carlisle,AR

    riverboat_20 Junior Member

    Hello to all, this being my first post but definetly wont be my last as long as yall dont get tired of my dumb ?'s

    I want to build a boat (who woulda guessed). Here is a picture of something similar to what i want to build
    [​IMG]

    Specs on what im looking at building 20' long 60"wide bottom 22" deep
    25 hp outboard motor. Flat bottom river boat.

    Im a good carpenter so I think i can handle building the plug. After it is built what are some preparations that need to be done?

    I know the mold comes from the plug and the mold will not actually be a part of the boat right? Fiberglass ect will be applied to the inside of the mold and will come off the mold eventually? What will the mold be made of and how is it applied? what are some of the different ways(products) to keep the mold from sticking to the plug. Same thing for the mold how to keep it from sticking to the boat?

    What type of fiberglass product should i look at using for this boat and a beginner?
    Can some or all off the products i need bo gotten at a big hardware store (lowes-home depot) or will i have to order them?

    Would building a scaled down model of the boat i want to build be best for me to start, like 1"-20' there fore the model would be a 20" boat (not sure whar size scale that is so dont pounce on me:confused: )


    I know this is alot mabey to much at once but I have a lot of ?'s. Ill try to keep it shorter from here on;)
     
  2. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    are you planning on making more of these boats or just 1,,are you making from your own plans"head" or making a copy of the boat pic'd,,
    and if your a good carpenter, why not just a houseboat?,,hehe,,that ?was just fer the laugh
    is money an issue,,have ya rolled around in fiberglass before,,heh,,and have you used the search on this forum yet,,,all that,,and i cant help ya,,hehehe,,well i could but,,,im not that ummmm,,,poetic,,and im pretty lazy,,and be ready,,cause im pretty sure Par, charm, and the guys will ask you all these ?'s and more,,,(and to tell ya the truth he's a little "snippy") hehehe ;) ,,jus kidding :D
    but you will be asked,,,so be ready ;)
    ohhhh ,,,you can hate me,,its o.k. im used to it hehe ;)
    nice meeting ya ;)
     
  3. riverboat_20
    Joined: Apr 2008
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    Location: Carlisle,AR

    riverboat_20 Junior Member

    Im making it from my own design from what ive seen on the river boats on the rivers in north Arkansas trout waters. Yes Ive used the search and have already learned alot. Probly will just make 1 boat but keep the mold in case i want to build another one mabey for a family memeber. In no way do i plan on going to any kind of production!
     
  4. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    That's the first thing you really get here.. More questions. Here one more.. What kind of river you gonne use it? Like Missisippi.., Yellowstone or ______

    You got to be telepate or something. Answered before saw the question:D
     
  5. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    I live on a river in WA and have several jet bots at my house (not all mine), I also lived in Arkansas for a short period of time and no one was ever able to answer my question as to why they use such narrow hulls.

    Here we use fairly wide hulls for less draft and stabilty while fishing. In AR they use narrow long hulls and you can't move around in the boat. We also use jet pumps so we can go almost anywhere in the river.

    The cost and effort involved in making a one off hull is pretty high, so if you're trying to save money it's not the rout to go.
     
  6. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    fer coon hunting and fittin between rocks,,and is like the hillbilly "rum runner" cars,,,fast and aerodynamic ,,hehe,,that and them ark. people always wanna stand in some kind of line hehe ;)
    (lived there a couple years)
     
  7. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    It sounds correct, but the rivers we run are shallower, rockier, tighter and nastier, with a large number of boat builders to help perfect the design.

    Here 99.9% of them are made from aluminum to take the abuse they get and there's no way you can get by with a prop, even a short-shaft outboard would be a no-shaft outboard in about 100 feet.
     
  8. riverboat_20
    Joined: Apr 2008
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    Location: Carlisle,AR

    riverboat_20 Junior Member



    They use narrow hulls to cut back on gas usage the 9.9 's they run will push them narrow hulls pretty darn fast without burning much gas. Think about it if you had a guide service with 20 or 30 boats wouldnt you want to cut you gas usage by half or more and on most days the boats on the river 50 to 75% of the boats are guide boats so thats why there are so many narrow hulls. One more reason is the locals that own there own boats may go on buffalo river and when she gets low some places may only be 10' -15' wide with a tree also intruding out from the bank in the way a wide hull would be hard to get down.

    Im not trying to save money I like to build stuff!!!! I have trouble finding a boat built the way i want it!

    Oh and one reason they dont run alot of jet pumps is when the river is low you have to run the shallow gravel bars and the risk of sucking up some gravel runs pretty high. Prop damage is minimal in shollw water if you know how to run the river ,you run the gravel side even if it gets shallow those boats dont draft but 2-3".Those river gravel will do minamal damage to a prop.If the river is low and you run the middle or non gravel side you risk hitting big rocks runing lower unit prop boat ect.....My uncle has been guiding on the White river his whole life ive learned alot from him in the short times ive been around him.
     
  9. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    RB 20

    Thanks for the info.

    I've been on those rivers and that's what confuses me, from 40 years of boating my local waters here and doing a little (and I admit very little) boating on the ones in AR, I don't see why a wider jet boat wouldn't be a better option for getting around in difficult areas.

    Fuel consumption is a big issue with a pump, so I can see why someone would go with a prop if possible, I would too if it was possible to navigate our rivers with one. Gravel isn't really a big problem for a pump if you're comparing it with a prop, as the jet has about ten inches more clearance than a prop, this does depend on the size of the O/B though. I can run through water that won't get your ankles wet with my jet.

    I don't want this to be an argument, I'm looking for the actual reasons each area use such a different style of boat to do the same thing. I think both types of boats have their advantages. Is there a HP limit on the rivers there, some lakes here have them, but rivers don't, so a common motor for a 20' jet boat here would be a 200hp tiller Merc or Yamaha. This boat would be 8' feet wide and very open so you can move around easily while fishing, some guide boats even go to 300hp on slightly longer hull.

    I like to fish some of the tighter shallower waters so my boat has a 90hp O/B and is a little smaller.

    Like I said before, this has confused me since I lived there for a short time about 12 years ago. I know there needs to be some logical reason for the difference, I just don't know if I've heard it yet.

    Please feed me more information on this.
     
  10. riverboat_20
    Joined: Apr 2008
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    Location: Carlisle,AR

    riverboat_20 Junior Member

    Buffalo river has a 9.9 restriction. But the biggest reason they run the narrow hull with a 9.9 -some personal boats may get up to a 25 hp is the gas b/c of the way the fishing is done .You fish a hole when you find the fish, floating down a mile or less usually and motoring back up repeatedly.Im not sure why there arent more jets I just know ive been told about the small river gravel as one reason as far as the fuel consuption idk but that is probly another reason.

    The boats are getting a little wider now though most are going to a 48" bottom instead of the 36" that used to be common. With a 48" bottom 20' long that 9.9 will push about 17-22mph and not burn much gas at all.
     
  11. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Thanks

    One thing I was told when I asked about it when I lived there, was the first guys to fish that method had a narrow boat and when the method caught on, others thought it was what you needed to use, so it stuck.

    We use a similar method to fish here, we drift down river using a smaller O/B (6 to 9.9hp) with a prop to control the boat speed and position in the river. These are sometimes mounted a little higher than normal so you can get into shallower water. In deeper slower parts of the river they're also used for trolling. The large motor with a pump is used to get up river, or at least to other locations, through shallow water, their may be up to 6 people in the boat so more hp is needed.

    Boats here have gotten wider over the years and it helps a great deal, so don't be afraid of going wider.
     
  12. riverboat_20
    Joined: Apr 2008
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    Location: Carlisle,AR

    riverboat_20 Junior Member

    Thats why i want to build my own but not get so big a 9.9 wont push it but to get a 60" wide i will have to build my own.I have looked around and i cant find anyone who makes them that wide.I have a 25 hp 4 stroke i will use own it unless i go to buffalo then i will put the 9.9 on.I found some who build the 54" for a reasonable price coustom built about $2500. I found one company that makes the 60" wide but to pricey for me $9000 just for the boat no trailer and no motor!

    Its not that hard to build the type of boat i want so ive been told by my uncle who built one many years ago from another boat they used for a mold. Im going to talk to him some more and learn what ever he knows . I just thout i would seek some proffesional help and mabey some good tips newer methods.
     
  13. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    To get back on subject.

    It would be very costly and time consuming to make a mold for just one or two boats, it would make the $9,000 figure look very reasonable. It's not that difficult to cut a 54" hull down the center and make it wider, so that may be an option. There are also some skiffs made in the South East that may have a hull in the size you're looking for.

    For more info on jet boats, or river boats go to some of the salmon and steelhead fishing sites in the NW.
     
  14. kengrome
    Joined: Jul 2006
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    Location: Gulf Coast USA

    kengrome Senior Member

    Hi riverboat_20,

    If it doesn't take me more than an hour or so, I will be glad to produce a custom hull design and panel cutting patterns for you (for free) and it will be exactly what you want -- assuming that instead of going with a plug and making a solid fiberglass boat you decide that what you really want is a plywood / epoxy / fiberglass composite sandwich hull with the dimensions and specs in your first post:

    20' long
    60" wide bottom
    22" deep
    flat bottom river boat

    You'll have to post some side view pictures of the hull shape you want before I start working on this, because I cannot tell much from that picture in your first post, and if I'm going to make this effort I want the results to look good to you.

    There are other options too of course ...

    If you want a design that will give you a shallower draft than a typical flat bottom boat I can put a bottom on it that looks somewhat like the attached image. This is commonly referred to as a Seabright "tunnel-stern" bottom. With the outboard engine down (in running position) this boat will draft much less than a flat bottom.

    A flat bottom will be faster, cheaper and easier to design and build of course ... :)

    By the way, the boat you asked for (flat bottom with a 5 foot wide beam at the waterline and 20 feet long) will not plane with a 9.9 HP engine so if you want it to plane you'll have to use your 25 HP engine. Just thought you should know this in advance, for whatever it's worth.
     

    Attached Files:


  15. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    I built a fiberglass flat bottom jonboat years ago using the foam log beam method that at the time was under patent by Carolina Skiff. Their patent has expired and the process is now public domain and anybody can use it.
    http://www.carolinaskiff.com/skiff/index.html
    The boat was 16' x 4'. Since the shape of the boat was developable from flat sheets (like plywood) with no compound curves, I skipped the process of plug making and made a mold directly of (1) A 4 x 16' wood base of 2-2x8's with 2x6 crosspieces every 24" that was set on short blocks at a good working height. (2) 1x4 frames were secured to the base every 2'. (3) I lined the frame with 3/4 x 1" strips every 6" fore and aft. A 3/4 x 2" strip was used in the chine at the bottom of the side so that the first smaller bottom strip formed a corner when joined to the 2" strip. This stuff was all fastened with sheetrock screws and Elmers wood glue. I would have used a pnuematic nailer or stapler if I had had it. (4) The strips supported a lining of 1/8" masonite that is coated on one side with a smooth white coating. The stuff is sold at Lowe's, Home Depot, etc and is 4x8', used for lining bathrooms etc. It's not the pebbly surfaced fiberglass stuff for commercial bathroom and kitchen walls, but the hard, dark brown masonite with a smooth white coating. It costs about $12 a sheet. I glued the masonite to the strips with Liquid Nails. (5) The corners were filleted useing either modeling clay from a toy store, or Bondo. The Bondo was mixed, spooned into a plastic sandwich bag, the top twisted shut, a corner snipped off the bottom of the bag and the Bondo squeezed into the corners like a pastry icing decorator thing for writing on cakes. The clay was rolled into pencil sized pieces and stuck in the corners. Both the clay and the Bondo were pressed into the corners and finished by sliding a tool socket of the correct size along the corner.

    A couple coats of wax and 1 coat of pva finished up the mold. The gunnel of the boat was just glass rolled over and the mold was bare wood there. That was coated with polyester resin, sanded smooth and then waxed with the rest of the mold.

    Since the back 2/3 s of the boat were straight with no curves, I made the transom on the mold movable so a shorter boat could be made with the same mold. Though I didn't use that mold much, I made others using the masonite stuff and and pulled 10-15 parts with no problems. The materials are very inexpensive and how much time is put into a project depends on the usual suspects, such as complexity of design, how fast you work, how particular you are, time available, etc.
     
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