designing a fast rowboat

Discussion in 'Boat Design' started by nordvindcrew, Oct 13, 2006.

  1. KJL38
    Joined: Jun 2008
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    Location: Tasmania

    KJL38 Junior Member

    IMHO 6mm and 4 oz should be ok if the gunwales are adequate to spread the loads. Maybe add some bracing to the foot brace as the heaviest loads are between them and the rowlocks.

    I used radiata pine to make the large traditional shaped stems which could be replaced with a much smaller strip shaving off a couple of kg. The gunwales are durian as that was the lightest timber in bunnings that seemed strong enough. Bottom board, bulkheads and end decks are 6mm plywood. I think with a bit of care it would be possible to be under 20kg(44lb)

    I don't use it as often as I would like but it's about eight years old now and doesn't show any stress cracks although it creaks if you plant an oar and it hits a rock shoving you sideways. The only damage has been minor from running into things and the cheap diecast rowlocks I originally installed that cracked within the first couple of weeks.
     
  2. nordvindcrew
    Joined: Sep 2006
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    Location: Marshfield massachusetts usa

    nordvindcrew Senior Member

    my strips are home milled and rather rough. The boat will be painted rather than bright finished, so I am tacking the strips down with galvanized finish nails. Seven strips to go and the hull is looking real nice to me at this point. Lots and lots of sanding and smoothing to be done. Re: glass cloth and epoxy; I,m a little nervous about using epoxy for allergic reasons but guess that I have to use it. We have a very rocky coast here, so wear is a worry. I'm thinking of several layers near the keel then one for the rest of the hull, inside and out. Light weight is not my first priority, so I'm thinking of using a bit heavier cloth than usual. Thoughts on this?
     
  3. NoEyeDeer
    Joined: Jun 2010
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    NoEyeDeer Senior Member

    How allergic are you? You shouldn't be getting it on your skin anyway. If the vapour is a problem for you, use a cartridge respirator.

    Sanding shouldn't be an issue provided that a/ your mixing is accurate (so you get a complete reaction) and b/ you let the resin cure fully (like a week or so) before sanding.

    If you just want wear resistance, I think you could use a normal weight inside and just increase the outside cloth's weight. Or if you're feeling flash, maybe even get a bit of Kevlar for the outside.
     
  4. KJL38
    Joined: Jun 2008
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    Location: Tasmania

    KJL38 Junior Member

    It sounds like it's coming together nicely.

    I coated the outside of mine with epoxy mixed with graphite powder. The graphite makes it self lubricating when I run over rocks and so far only have a lot of scrape marks and no zippers in the glass.

    Heavier glass is harder to wet out so more layers may be easier. I used a single piece of extra wide glass on my boat and it made doing the inside difficult, especially near the ends. If I were to do it again I'd use narrower glass and overlap it in the middle. On the outside if you did a strip each side overlapped and another down the center you would have three layers where you need it without adding too much weight.

    If you have allergy problems you may want to wear a respirator when sanding the cedar as I have heard of people having problems with the dust. To clean up runs etc in the epoxy I used a shave hook while it was still green and found it much quicker than sanding and it didn't produce dust.
     
  5. nordvindcrew
    Joined: Sep 2006
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    Location: Marshfield massachusetts usa

    nordvindcrew Senior Member

    progress

    The false stem is on and waiting to be faired, same thing for the skeg. Outside of hull is mostly sanded but needs some fairing. Weather permitting, I'll do that on Wednesday. I like the idea of overlapping the glass in the middle. Checked out kevlar tape: @ $5.00/ ft it seems affordable to do a strip down the keel. I've been using a respirator while sanding, so no respitory problems. The weather has almost closed me down for this year, so I guess I'll cover her up and wait for spring. I went to a local race on Saturday, most of the old timers have retired and their places haven't been filled by younger rowers. Gigs and multis make up most of the fleet now. Even more incentive to finish the boat and try to compete ( or at least participate ) one more time.
     
  6. j42
    Joined: Dec 2016
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    j42 New Member

    still fast with more displacement suggestions?

    I've enjoyed this thread, thank you all.
    I was wondering if you'd have thoughts on the fastest rowing boat that would take four adults, rowable by one or two, launchable up and down a ramp by one. I'd got to lightweight builds of either Iain Oughred's Acorn 17 or a stretched Cosine Wherry. NoEyeDeer's boat looks great, but I need more displacement. The constraints are it should be happy in the great river race on the Thames, but also easy to use as an individual
     
  7. keith66
    Joined: Sep 2007
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    keith66 Senior Member

    I have done the Great river race 6 times starting in 1987 in a Pete Culler Whitehall, she was a fast boat but rated terribly under the GRR handicap system. Other similar boats since have also been rated poorly. If you look at the results you will see certain boats or classes always feature high up the fleet.
    The Hanningfield Skiff is one of the fastest, i used to build these but sold the mould earlier this year, at 18ft x 54" beam she is a good load carrier & can carry a crew of 4 strong men. The other boat that has actually won the race numerous times is the Maggie, she has always been entered as a "Dinghy" but is actually a standard 14ft Cosine wherry, Her crew the Graham buoys have worked out a very good system of doing the race. They are both fine boat rowers & are ex team GB, big strong men & very fit. They scull with long oars very highly geared using two tiny girls as cox & passenger. They do not stop rowing & use bladders to drink on the go. Basicaly they drive Maggie at max hull speed or more for the duration of the race & are very hard to catch!
    I built a stretched Cosine wherry for a customer a few years ago & have recently built another for myself. She is stretched to 17ft 6" & is a good boat. Trouble is the Cosine wherry has enough displacement for two plus gear but you would be pushing it with a crew of 4 people especially if they were large. This applies equally to the stretched version the increased length increasing the displacement a relatively small percentage. Other option is to do what we did with the whitehall, use a tiny cox & three rowers one of whom sat as a passenger at any one time, this way we rowed 1/2 hr on 15 minutes off then swapped over. Might enter her next year!
     
  8. j42
    Joined: Dec 2016
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    j42 New Member

    I built an Oughtred Sooty tern and had rather a leisurely race this year with three sculling a spare rotating in, all rather unfit, and two enjoying the ride. It's beautiful, but I it's too big to launch and row by myself, hence the thoughts for something like a paulownia strip Cosine wherry or lightweight built Acorn, which looks Whitehall like. Could you put the wherry in and out of the water by yourself?
     
  9. keith66
    Joined: Sep 2007
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    Location: Essex UK

    keith66 Senior Member

    Yes i can launch & recover her on my own, she has her own launching trolley.
    For a race like the GRR i would think the Cosine wherry to be overloaded with four adults, she will carry the weight but will sit low in the water, then its going to be a struggle even with a good boat under you.
    Bear in mind that the stretched boat i have is a fibreglass version. Not a light material.
    She weighs in at 80 kgs (176 lds) which is considerably more than the standard Cosine the designed weight of which is 49kgs.
    Mine is 3ft 6" longer but the increase in displacement due to increase in length is not that great so her crew capacity remains the same.
    Building in GRP, Gelcoat is heavy, just the gelcoat in the mould is 7kgs, the flowcoat on the inside is 7kgs, so 14ks of ballast! then you use 25kgs of resin, I used a high percentage of Biax cloth & very light CSM between the layers to keep the weight down. If i had laid the boat up using CSM alone she would have gone over 120kgs. Far too heavy.

    First time she raced was in the round canvey race a 14 miler. First 3.5 miles were against an incoming tide & wind, Its a pursuit race so smallest boats are sent first followed by the faster & larger ones. We got overtaken by the first four oared boat at half a mile but caught up & passed him a while later. At 3 miles we were still at the front of the fleet only getting passed by the gigs & sliders when we got out into the rough water of the estuary.
    I was rowing with my son who at 20 is a strong lad but had never rowed the boat before, He wanted to go fast but i was worried i might conk out being rather unfit & suffering from bad arthritis in one arm, so i set a steady pace & it being very hot we drank often. At the time i was very surprised to be still at the front of the fleet at that stage, I think with two good rowers we would not have been caught at all.
    It so happens that it was definately my last rowing race as the old injury & arthritis has now reached the stage where it would be foolish of me to race again.
    It showed that the Wherry is a fast boat!
     
  10. RHP
    Joined: Nov 2005
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    RHP Senior Member

    Keith, where would someone buy a Cosine Wherry or that kind of fast, traditional rowing boat in the UK? I spent hours rowing in classic wooden rowing boats when I was young (they weren't classic at that stage...) and nostalgia is tugging at my sleeve...
     
  11. John Perry
    Joined: Nov 2003
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    John Perry Senior Member

    I have now completed a small rowing boat and last week we completed a maiden voyage which was an approximately 60 mile camping trip down the river Thames in UK, together with 14 other small boats. We started near the source of the river, just downstream from Lechlade in Gloucestershire and completed the trip a few days later by arriving at the Beale Park boatshow which is held annually on and around a lake that connects into the river near Pangbourne. We entered the boat in the amateur boat building awards competition which is held annually at the Beale Park boat show and won the prize for most innovative boat. This year there were only four entries, three entries having cancelled because the boats were not finnished on time and since there are four prizes each year all entries this year received a prize, which is a nice result.
    [​IMG]

    Just to check that the boat actually floated the right way up we did launch it briefly on our local water a few days before starting the Thames row - the picture above shows it on the slipway at Mountbatten near Plymouth UK a few minutes before floating for the first time.

    The boat is about 15 and a bit feet long and designed to be rowed by one rower on their own or one rower with a passenger, hence it has two locations for the rowlock outriggers. It has a sliding rowing seat that can be locked for fixed seat rowing but so far we have used it almost entirely sliding. There is also provision to experiment with a sliding rowlock arrangement should we wish to try that, but that would have to be without a passenger. The design waterline beam with a single 80kg person rowing is 666mm, adding an 80kg passenger increases that to 751mm. I weighed the finished boat with a good scales and found it weighs 43.5kg without the carbon fibre oars (which add just a bit under another 3kg) The weight predicted by the computer was 41 kgs, the small difference is probably mainly a bit of extra epoxy resin/filler here and there. The boat is built from good quality 3mm marine plywood and is externally sheathed with glass fiber and epoxy resin. All the plywood for the boat was cut by waterjet cutting from files generated by Solidworks software. Earlier on this thread I have a post with a picture of all the plywood parts as delivered from the waterjet cutting company.

    Soon after setting off on the Thames trip we found that the rudder was too small to control the boat properly on the twisty upper reaches of the river. This was not a complete surprise. After I had cut out the rudder blade from a piece of old oak floor board I realised that it was weakened by a large knot that had been filled with some kind of wood colored filler and feeling too lazy to start again with a new piece of wood I just cut off the end of the blade. My thought was that if it did prove adequate that way it would be a bit less drag in the water than the blade as originally intended. However, after a few hours of frustration, colliding with overhanging tree branches on the river, we found a discarded bit of plank by the riverside and tied that onto the blade with string which allowed us to complete the trip although I think we had some drag from that plank. Later on we tried the boat both with a passenger on board and rowing without a passenger and discovered that the small rudder blade is adequate for solo rowing. It is only when the boat is loaded with a passenger as well as the rower that a larger blade is needed so I am thinking about making a streamlined fibreglass sleeve that when necessary would enlarge the existing small blade by sliding over it and locking in place with a small pin or suchlike.

    Apart from the rudder blade difficulty the boat performed well, although neither myself or Josephine know much about rowing to judge that. We did briefly lend it to an experienced rower who told us that it was set up about right with regard to rowlock and foot plate position and he thought it was a fast boat considering that it is only a bit over 15 foot long and has a relatively stable hull shape. He did say that he would prefer a boat that could be rowed without needing a rudder. I expect the reason the boat needs a rudder is because the transom stern easily slips slideways over the water whereas a canoe stern or a 'whitehall' style stern would grip the water and give better directional stability but would also inhibit making a really tight turn should you need to do that. I chose to have a transom stern, albeit quite a small transom, partly because I liked it aesthetically, partly because it gives a bit better pitch stability which helps with a short row boat and partly just to make it a bit different to the more useual canoe or whitehall sterns.

    We found that the boat has adequate storage space to carry food and camping equipment for a trip lasting a few days. The open cargo space behind the passenger seat holds our tent, a few dry bags and a plastic box for food, another plastic box with stove, mugs/plates and more food sits down in the bottom of the boat under the sliding seat. Sleeping bags and air mattresses are just stuffed through the round plastic hatch in the foreward bouyancy tank.

    You see from the picture that the boat has a pair of wheels for moving it around on shore. These have proved to be very handy and so far have been used in preference to the more conventional trolley that I also made for the boat. These are wheelchair wheels with quick release axles that can be clipped to the boat in a matter of seconds. The bearings for these wheels are not waterproof so when launching the boat we wheel it into a position where the wheels are just clear of the water then take off the wheels and lift the boat from the bow so that the stern floats, then push it out onto the water. The transom stern helps with this since it floats the stern of the boat in little depth of water. I have made a detachable towbar that connects the boat to the seat pillar of a Brompton folding bicycle. I have tried that for a short distance on the quiet road outside our house, not sure about it for busier roads!

    The outriggers for the rowlocks, which I think are called 'gates' since they are the type that lock over the oars, are designed so that they can swing inwards when entering locks or coming alongside the river bank. These outrigers do not obstruct the interior of the boat when retracted by swinging them inwards. The oars remain in the gates and lie fore and aft above the side decks when the outriggers are retracted. This arrangement works well and is possibly the reason we won a prize for most innovative boat. Throughout the Thames trip I dont think we ever bothered to take the oars out of the gates, even when lifting the boat onto the river bank for the night.

    Project completed on schedule and performing well with minimal need for mods!
     
    Last edited: Jun 5, 2017
  12. Clinton B Chase
    Joined: Mar 2005
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    Clinton B Chase Senior Member

  13. IronPrice
    Joined: Jul 2017
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    Location: NZ

    IronPrice Senior Member

    Wow. What a fantastic thread. I've thoroughly enjoyed reading it and learned a lot. I'm from a coastal town called Nelson, which is at the top of the South Island in New Zealand.

    I want to build a single rowing boat for coastal fishing. I'm interested in trolling lures for some of the local coastal species we have.

    I would appreciate some advice on the suitability of design I have settled on. CLC's Expedition Wherry Chesapeake Light Craft Ocean Rowing Wherry http://www.clcboats.com/shop/boats/rowboats/expedition-wherry.html

    It's described as a more seaworthy Wherry than the Annapolis wherry which was discussed in this thread, with a bigger pay load and generous storage lockers, one of which I could turn into an ice box for the fish. It has a dry deck with small foot well, which I could fit a pump in to control any water that comes on board. I can see plenty of places to fit a few rod holders.

    With my limited knowledge it looks well suited to my needs, but I would appreciate hearing more experienced opinions.

    I want a boat that I can row comfortably at 3 or 4 knots for a few hours pulling a couple of small fishing lures. I'm fishing with light gear (about 10lb drag)_ so the fish can't exert enough force on the boat to affect stability.

    I'm about 6 feet tall and about 220lbs with long arms for my size.

    The Expedition Wherry is pictured with outriggers and I'm unsure how compatible these would be with fishing. On a simple boat with gunwale mounted rowlocks if you catch a fish you ship the oars by resting the handles on the floor of the boat. This gets the oar blades out of the way Is that possible when outriggers are used?

    We get a daily sea breeze of about 15 knots which produces a short sharp chop of about two or three feet. I don't expect to be able to fish in that chop, just to cope with it if I get caught out because the sea breeze picks up early (there is no forecast for it). If that happened it would be a following sea until I reach shelter.

    I'm an experienced kayak fisher but I have minimal experience rowing. We do have extensive waist-deep sheltered water that I can practice into start with - no fish there though!
     
  14. Tallman
    Joined: Jun 2011
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    Tallman Junior Member

    I'd say the CLC Expedition Wherry is a little too low and small for what you are describing. The CLC wherries tend to have low freeboard and are more for protected bays.
    For sliding seat boats, you may want to consider the Wayland Marine Merry Wherry types, like the Merry Sea kit. I built Ken Basset's Firefly double from plans, which is very similar when decked, and I can bash to windward in it in pretty good seas. These all use the Piantedosi RowWing unit. The riggers are fixed, and shipping the oars might result in nearly rolling the boat in nasty swells. So that's an issue.
    The CLC Dory will be great if seas get hairy but is pokier than the above boats (wider, shorter). On the other hand, it is also more stable. It can be rowed fixed seat too. Shipping its oars even with the riggers wouldn't be a problem.

    In general, you can go a bit narrower if you can get the center of gravity for rowing down lower.
    In this category, for fast fixed seat, are the guideboats. Adirondack Guide Boat Co. has the Vermont Dory and 15' guideboat (in Kevlar I think) that are seaworthy, light and fast. You can also build a cedar one, although if you are going to have fish slopping around in it you may want to go with the sturdier, easy care synthetic materials. They look like they have low freeboard but ride out heavy seas really well.

    Other fixed seat options, which as noted is a consideration if you are fishing and need to scramble about easily without the riggers intruding, include Clint Chase's Drake 17 and Fast Drake. They come as kits and, built light, can kick along at your required speed for hours. They may be the best option as you could mount a sliding seat rig in them also (and they are wide enough that shipping the oars wouldn't destabilize it much) but have the fixed seat option too (and a small downwind sail option I think). There are others I'm not thinking of at the moment , but finding something fast, not a huge chore to build, seaworthy enough and not heavy (e.g. 115 lbs or less) can be a challenge.
     

  15. IronPrice
    Joined: Jul 2017
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    Location: NZ

    IronPrice Senior Member

    Thanks Tallman.

    CLC describes the expedition wherry as having "open-water ability". Are they stretching the truth a little?

    I will be fishing a coastal bay, rather than true open water. It's called Tasman Bay.

    Google Maps https://www.google.co.nz/maps/place/Tasman+Bay/@-41.0573268,173.0152823,10z/data=!3m1!4b1!4m5!3m4!1s0x6d3c0a584f9b763d:0x2a00ef86ab64dc80!8m2!3d-41.0457625!4d173.2934086

    Regarding COG, when fishing I don't want to be too low down as I need to be ale to keep the rod tip high, without too much angle. I thought a slightly wider/higher boat would allow this? There wouldn't be an scrambling about after fish. I would keep the rod holder positions as close as they can be without interfering with rowing, gaff the fish and then stow them in the stern locker. All doable seated

    I'd happily consider a guide boat but I'm a little concerned about the windage of those raised ends - but perhaps they are an illusion caused by the low free-board at the center. I'm also wondering how a transom-less design would cope with a following sea? I need storage lockers for gear and fish.

    The Merry Seas does look good, -its a similar design to the expedition wherry but 9" longer and 3" wider . The problem is that shipping costs to New Zealand for a kit are horrendous and also attract sales tax, import duty and clearance fees. and I don't see and option for plans?

    Whatever design I go with I need to build from plans. I'm relaxed about strip plank or stitch and glue, although plywood is easier to source here than strip material.

    I would definitely use durable finishing. For example Bilge paint in lockers, non-slip foam (e.g. SeaDek) in the cockpit and durable paint elsewhere.
     
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