fishing offshore in a rowboat.

Discussion in 'Boat Design' started by coopscraft, Dec 6, 2013.

  1. KJL38
    Joined: Jun 2008
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    Location: Tasmania

    KJL38 Junior Member

    Oregon fishing

    You might like to read some of the oregon fishing stories at http://www.capefalconkayak.com/ The lightweight kayaks do have an advantage in being able to be launched from very small sheltered corners.
     
  2. coopscraft
    Joined: Dec 2013
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    Location: oregon

    coopscraft Junior Member

    particulars

    I am enjoying all the sugestions and links. Here is a rough verbal sketch of where I am so far on the project. I have to finish a few things before I can actually start bending wood, a kitchen table being one. I. Was thinking I might build a simple scale hull and throw it off the jetty with various weights, control surfaces and sails to get some intuition about how big waves act on a small boat. Iv been watching kayaks and power dorys on youtube as well. It looks like a peaking wave has local current sliding towards the trough forward and backward at the same time. A boat long enough to reach both currents can be rotated. It seems like a displacment craft in this position steered from the middle by oar or paddle can be prepared by having a lot of rocker and a short waterline length. This gives the crew more yaw strength. However, the downside is that, with no planing surface there is no controlled surf option. The boat would basically be forced to drift over the crest like a river dory through rapids. Perhaps moving th LCB aft of center and minimizing rocker aft while having prodigious rocker forward would make a good compromise. As has been said before, launching from the beach does appear to bring good fishing a lot closer. A kayak with its low weight and pointyness would be a simple solution and the hull could be had cheap in plastic from any sporting goods chain-or craigslist. However, the ergonomics of a kayak look a little like numb legs to me. I could be wrong. But if its anything like sitting on a ballance beam with legs up in front, I'm sure I would be miserable. So what if a rowboat were built light enough to carry down the beach, and with the skirt to prevent shipping water, a comfortable fixed rowing seat and large oars. A bow that was high enough to be dry in small surf, but a low depth midship for windage. A flat bottom for landing on sand. A narrow waterline for easy forward movement. This would be less stable. I have considered this. I currently own a twelve foot doryskiff with a bottom 2ft wide. It is very tender to most people but I don't mind it a bit. One thing a kayak can do that a wider row boat can't is roll to rightside up under paddle power. The rower will need to be able to quickly escape the skirt and re-enter in case of capsize. The boat can be designed to right easily with minimal shipping of water with side decks and skirting. A boat can have some ballast and still be light. Water ballast tanks can be hand filled at water's edge and latched into place. I should think one or two cubic feet would have a positive affect on stability without being much of a burden (128#). I can't seem to decide on 18 or 24 or 30 inch wide bottom. I'm thinking 12 inch flair and 18 inch depth midship. 18 inches would be tender but 30 inches would require more muscle. I can put the oarlocks outside the rail so the narrow beam of a 42 inch boat would not interfere with rowing. Length on bottom I'm thinking 14 feet. More than 14 ft and surface friction makes achieving hull speed unlikely for me anyway. Faster is better. Too much surface will slow me down. Also I think longer would not turn easy on command. Also to turn easy I'm thinking 6 inches of rocker forward might be indicated. Pacific power dories have a lot more but they are a lot larger overall. Perhaps 3 inches aft? A small hook of an inch in the last two feet for planing in surf? Planing dynamics are complex. Perhaps I should leave it out of my design. I still have to work out the numbers for LCB. Id like to have a boat that is efficient a little faster than hull speed. 1.34√14=5 7 mph returning downwind would be convenient. A stowable rig or kite could outrow me at the end of the day. This boat should be a double ender. My inclination is to pull way back from a true dory's 2 foot stem overhang since im guessing this adds a lot for a breaze to grab onto. 12 inches? Each stem profile should have a pleasing round shape.A fuller bow and stern should provide ample boyancy on end. I read years ago that a wave colapses when the hight reaches 1/7th the length of the base in direction of travel. A light displacement craft 16 ft loa with 27.5 inches freeboard at the stems should then reach the crest of a colapsing wave of the same base length. A longer base would mean the curve of the trough would be flatter but the hight of the wall would increase. Is there a formula for predicting these?

    Comparison particulars to inside of plank. Plank is lighter than water.

    Option a
    Loa 16 ft
    Lob 14 ft
    Beam 54" (cross section of midsection side is a circular arc with center located by geometric construction from a line level with sheer and a radius passing through the midpoint between the sheer and chine accordingly the side should be vertical at sheer and curve inword to the chine.)
    Bob 30"
    Depth midship 18"
    Rocker forward 6"
    Rocker aft 3" or 6" ?
    Stems 30" above baseline (24"/ 27" above bottom at stem)
    Max capacity estemate
    1.25(2.5+4.5)/2 = 4.375= midsection area factoring for rocker
    (16+14)/2=15=length
    15*4.375*.625=41.02= volume below sheer midship
    49.21*64/3=875#= max load calm water per uscg backyard boatbuilders handbook

    Option aa

    All same as in a except beam 2/4
    Capacity by same method 750#

    Option aaa

    All same as in a except beam 1.5/3.5
    Capacity by same method 625#

    Option aaaa as above
    Loa 18 ft
    Lob 16 ft
    Beam 3.5
    Bob 1.5
    Depth midship 18"
    Stem hight 33"
    Rocker 6"
    Max capacity 708#

    Notes. I have used .625 or 5/8 as a factor to account that the lines won't be a triangle from midsection to stem. This may turn out a bit on the full side.

    First inclination for construction is 3/8in glued lap in 5 laps over permenant plywood watertight bulkhead frames creating compartments full of styrefoam. No mt space. Strip planking would also be a great option.

    Cockpit with space for two rowers. Detatchable waterproof skirt fitted to coaming. Designed for easy escape.

    Boat is hand launchable by using a bigwheeled two wheeled cart that supports the weight near the balance point.

    Weight of bare hull is getting out of hand.
     
    Last edited: Dec 24, 2013
  3. KJL38
    Joined: Jun 2008
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    Location: Tasmania

    KJL38 Junior Member

    Adirondack guideboat

    I have an Adirondack Guideboat built to these plans http://www.guillemot-kayaks.com/guillemot/catalog/boat_building_plans/adirondack_guide_boat_plans
    I found it handles waves surprisingly well with the narrow flat bottom enabling surfing and the sheer curve matching the wave, trailing the oars works as a rudder. It also takes waves from the side quite well, remaining upright unless the wave is breaking enough to get water aboard in which case it starts to tilt making it quite dry for the conditions.

    If you combined a hull like this with end and side tanks and a minimal cockpit you would have a boat which would drain when righted from a capsize and could be re-boarded. Similar to this design http://www.angusrowboats.com/expedition.html
    You can see it being righted in the video at http://www.angusrowboats.com/index.htm

    There are a couple of hull shapes at http://flo-mo.weebly.com/two-sheet-boats.html that you may find interesting.
     
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  4. coopscraft
    Joined: Dec 2013
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    Location: oregon

    coopscraft Junior Member

    That expedition is rugged. The adirondack guidboat is gorgous and the two sheeters are elegant. All different. All really cool. So many boats so little time. But, ideas from each could be helpful. I could see myself building them all one after another, but then I have too keep my dayjob too. The expedition is functionally the closest boat to my goal iv seen yet.
     
  5. MoePorter
    Joined: Nov 2012
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    Location: Oakland,CA

    MoePorter Junior Member

    Now you're getting somewhere...Great to see initial specifics trial ballooned for our enjoyment, thanks for "open sourcing" your design process.

    Couple things - 1.what's your maximum acceptable boat weight?
    2. I don't know how you rig a skirt to a single rower, much less two, the rowers body movement plus the relatively large cockpit would seem to require a large skirt that might hinder the recovery process - any examples of how this has been done?

    The expedition kayak/skiff is a very interesting hybrid - thanks for the link KJL38. Certainly a solution to my skirt skepticism...I love the stability of the relatively wide beam which would be very useful for fishing & comfort related movements. The cockpit might need a redesign for your use. Moe
     
  6. coopscraft
    Joined: Dec 2013
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    coopscraft Junior Member

    Weight, I could be wrong but I suspect more than 300lbs would be hard to roll over dry sand. On flat water 300 lbs is nothing. In 4 foot surf with 4 oars I don't know. In a curl, it could be a permenant headach. I'm talking bare hull here.

    Skirt, my thinking was a water resistant fabric with an elastic band or draw string arround the rower, with enough baggyness arround the hominid to allow for rowing motion. A little water would get through, maybe a few quarts instead of feet.
     
    Last edited: Dec 24, 2013
  7. erik818
    Joined: Feb 2007
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    erik818 Senior Member

    300 lbs will be heavy to roll to the water by yourself or with a less strong helper. I'd put the limit at 200 lbs, with 150 lbs as a target, excluding anything that can be removed from the boat when rolling it to the shore. At least where I live, nature isn't very helpful with providing gentle, flat and hard surfaced slopes down to the sea. If 150 - 200 lbs means a shorter boat than your spec, so be it. Your'e not going to use the boat much if it's too heavy anyway.

    My preferred building method would be wood strips glued with epoxy and sheathed with a thin layer of glass/epoxy. In Sweden I would use spruce (Picea abies)or aspen (Populus tremula), probably less than 8 mm thick strips. I understand that red western cedar has similar or better properties for small boats.

    I've no experience with any decent surfs, just general abuse of boats. Still, I'd rather build the boat light and maybe too fragile than make it too heavy.

    Erik
     
  8. MoePorter
    Joined: Nov 2012
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    Location: Oakland,CA

    MoePorter Junior Member

    I have to agree with eric 818 as to weight - personally I'd aim for under 100lbs, be happy with 125lbs & saddened but accepting of 150 lbs. In my experience any beach launched craft, at some point, has to be lifted either entirely or mostly...I think any weight above 150lbs would be take 2 strong folks -the cart falls over, there's a log, short drop whatever. I can load 125lbs on a vehicle rack by lifting one end at a time - but I don't like to...So IF you want a beach launchable craft I'd get very focused on weight as a primary design goal.
    I have a Klepper double kayak with an open cockpit 101"x16.5" (2565mmx419mm) it has a spray cover & it works OK for rain & spray - it's a pain to rig, was expensive and given the Kleppers high gunnels uncomfortable. The limiting factor with a big spray cover is it has to come off quickly in an emergency - so for it to stay attached to the coaming with a lot of heavy water pushing against a large surface area the required strength of the attachment would pose a release hazard in an emergency. Not saying there isn't a spray cover solution but I'd approach it with two small cockpits as close to classic kayak size as possible and I'd spend a lot of time thinking about complete/partial self draining cockpits before I'd go that route! Incidentally the Klepper weighs 79 lbs (35.8kg) and while not a pleasure to handle solo with a cart is OK -

    Here's some interesting solutions to your goals - the first two take one path & the Ian Oughtred designs quite another...

    I'd suggest the first two are more kayak based in their low weight, rowing position, portability, wetness and related to wetness - recover-ability. They would tend to go through wave tops and thought has been given to deal with water in the cockpit as well as capsize recovery. They are particularly helpful with regards to their respective cockpit design.

    The Oughtred designs are heavier, much dryer, much more carrying capacity & are a traditional approach to small surfboats. I think a capsize would be very difficult to recover from unless it was laid out like rescue surfboats with turtle backs at both ends & a small draining cockpit. They could be built considerably lighter than his weights of 140 lbs (72kg) to 180lba (82kg) although any self-righting structures would add weight so I'm not sure how light you could go...They would be great to sail however & way more comfortable.Moe

    KJL38 sourced this Angus Expedition Rowboat-
    http://www.angusrowboats.com/images/expeditionPlans.html


    Decked sailing canoe with a fishing friendly cockpit layout.
    http://www.solwaydory.co.uk/?page_id=35

    Oughtred designs -
    http://nisboats.com/oughtred/pics/large/largedwgs/Elfyn-1.jpg

    http://nisboats.com/oughtred/pics/large/Elf-1.jpg

    http://nisboats.com/oughtred/pics/large/largedwgs/Whilly-Tern-2.jpg
     
  9. coopscraft
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    coopscraft Junior Member

    Those elves look real nice. Just found out on my related thread that waves are shaped like a hyperbolic sine-cool
     
  10. coopscraft
    Joined: Dec 2013
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    Location: oregon

    coopscraft Junior Member

    Just lost a mega post trying to reconstruct in pieces.

    Plywood and lightness:

    A/ is it true what I hear that the glue in exterior grade fir plywood from the pacific northwest is as waterproof as marine plywood?

    B/ is 1/4" plywood structurally sufficient in surf?

    A verbal sketch of the proposed structural development follows
     
  11. coopscraft
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    coopscraft Junior Member

    Assume lines similare to those previously mentioned. The core of the structure is a punt-shaped inner hull in half inch plywood(or 3/8?). The transomes are raked 45 degrees and are proud of sides and bottom. The bottom is proud of the sides. Wood frames are epoxy glued and screwed to the proud portions in order to form strong joints. The sides of the punt have a constant 30° flare and the sheer and chine of the punt run parallel to the sheer and chine of the outer hull. Footholds for rowing are anchored to the sides of the punt. The inner hull is reaches 5ft aft and 3ft forward of midships in order to allow for balance over the center of buyancy. The inner hull sits 6 inches above the inside of bottom. A plugable scuppered aft makes the the boat self bailing. I don't like raising the floor for stability reasons. But, I think shipping water would be worse.
     
  12. coopscraft
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    coopscraft Junior Member

    Positioned vertically on the centerline is a 3/8" plywood panel epoxy bevel scarfed to run from the stem to stem reaching from inside bottom to inside deck. It has cutouts for the inner hull and fore a and aft watertight stowage. The section frames are similarly made from 1/4" plywood. Each is glued and screwed into place with epoxy and wood frames. Circles can be cut out of the section frames to save weight leaving at least 4" arround the outside. Stringers run in notches cut into the frames as nail/glue surfaces for 1/4 ply glued lap planking.
     
  13. coopscraft
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    coopscraft Junior Member

    The half inch bottom is put rightside up on the strongback. Then the center panal is added to the bottom with stems. Then the preassembled inner hull and storage compartments. Then add the plywood frames. Install chines and stringers. Plank the sides. fill all empty space with pourable foam flotation install the deck. Install outer stems.
     
  14. coopscraft
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    coopscraft Junior Member

    A coaming on the ends of the cockpit should help with dryness. Leaving a smooth spot midsips will allow the boat to drain when healed over60°
     

  15. flo-mo
    Joined: Jul 2010
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    flo-mo Junior Member

    From the U.S. coast guard website:

    Lines plans of two surfboats (not matching the OP's SOR but maybe interesting for studying the type of boat):

    26' Monomoy Type Pulling/Sailing Surfboat:[​IMG]

    27' Jersey/Long Branch Type Pulling Surfboat:[​IMG]
     
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