• 4th April 2010 - By greg

    knockdownShore

    During offshore sea trials a few days ago, I encountered a somewhat serious problem. Up until this point, the most wind WiTHiN has ever encountered is about 10 to 15 knots. During a run offshore on April 1st, I encountered 20 knots of wind and WiTHiN broached and was rolled to 45 degrees where she stayed. The water level was up to the bottom of the starboard port lights. I was unable to steer out of this orientation and I drifted safely back into the inlet just missing a rocky point. The photo attached is a frame from a cockpit video I was shooting at the time.

    The YouTube video of the trip:

    Here are some background details:

    1. During even the smallest amount of wind, WiTHiN always weather cocks so that it is abeam to the wind.
    2. During 10 to 15 knots of wind beam-on, WiTHiN will heel about 10 degrees or so.
    3. When abeam to 20 knots of wind, WiTHiN will drift at a speed of about 1 knot. When facing directly upwind, she won’t drift very much, but this is hard to measure because the only way I can maintain an upwind heading is to pedal forward. When drifting, she quickly broaches.

    Conditions at the time of the knock-down (taken from historical data from a near-by ocean weather buoy and a radio weather report immediately after the incident):

    Date & time: April 1st, 2010, 11:52 am PST
    Wind: 20 knots from the South
    Wave height: 3.5 meters

    Details:

    I was staying in WiTHiN docked at the Marina in Ucluelet. The Marina is situated on a protected peninsula 2 nautical miles north of the entrance to the Ucluelet inlet. The original objective of the offshore sea trials was to pedal a distance offshore and sleep overnight in WiTHiN, but the weather forecasts were for more gales and a storm warning, so staying out all night was not a safe plan. When I arrived in Ucluelet on March 29th as Clive was sailing Theodora from the east side of the island through the storm, I could actually see the spray puffs from 6 meter waves crashing against the reef from the far end of the inlet 3.7 nautical miles away! Up to that point, I had made day trips out into the swell past the entrance to the inlet for 3 days and had spent considerable time maneuvering WiTHiN through 4 meter swells that entered from 2 channels which created an unpredictable mayhem of criss-crossing waves. So far, WiTHiN handled the conditions very well.

    On my 4th day – Thursday, April 1st, a storm was forecast for the afternoon, so I thought it would be a good chance to venture into the channel and finally experience how WiTHiN handles some wind. Up to that point during the 3 days previously, the wind ranged from calm to 10 knots. The remnant swells from a storm 4 days ago and a gale up north were still very big, averaging from 4 to 6 meters.. Clive stayed at the marina to replace some fuel filters on Theodora and I headed out into the swells by myself.

    On my first entrance into the channel, I was becoming concerned about how quickly WiTHiN was turning sideways to the 10 to 15 knot head wind. So, I backed into the entrance of the inlet where I had ample sea room and still some swell and wind, and I deployed my drogue to see if the drogue would pull my bow into the wind. WiTHiN stayed abeam to the wind with the drogue dragging up wind off the port side. I realized that maybe the sea anchor would provide more resistance, but there wasn’t enough room between buoys and the shore to play around with the anchor. Plus, I was moving downwind and into the channel at about 1 knot due to the tidal current. I put the drogue away and headed back into the channel and swell.

    When I exited the inlet, I proceeded up-wind toward a rocky island we called “sea lion island” due to the large number of barking sea lions on the rocks that we had watched there during previous days. The swell today was a bit less than previous days at 3.5 meters according to the weather forecast and weather buoy data for that date and time. The direction of the swell was coming directly toward me in a more uniform fashion compared to the previous days multi-direction. When I reached mid-channel, I turned to port and spent a couple of minutes pedaling abeam to the wind and seas. I noticed that the wind was picking up because WiTHiN rolled to port more than usual due to the wind. When I went to make another turn to port to head down-wind, I was alarmed by how difficult it was to make the turn. I had to use full rudder and really had to stomp on the pedals. WiTHiN’s bow moved slowly and reluctantly around to the left, and I started to pedal down wind, back toward the entrance to the inlet.

    As I struggled to get the bow going left, the situation felt very familiar to me. I realized that it was the same feeling I had with Critical Power 2 trimaran (24 hour human powered boat world record) during a windy training day on Whitefish lake. The high wind had turned CP2 abeam to the wind and I was unable to make a turn either to port or starboard and was blown into shore. It feels like the rudder isn’t working, and additional power added to the pedals does nothing to help activate the rudder.

    I was now noticing white caps just starting to appear.

    I was heading directly toward the rocks on the North East side of the channel, so I started to make a slight turn toward port again to alter my heading toward the entrance of the channel rather than the rocks. I was immediately blown around to a position perpendicular to the wind (broach). I was very alarmed when WiTHiN rolled to 45 to 50 degrees with water up to the level of the port lights. I quickly closed the pilot hatch (in case of a complete roll – unlikely, but I’m always being safe) and tried to make a turn to starboard. The bow was not moving an inch. I cranked on the pedals as hard as I could and I could still not move the bow a fraction of an inch. The rudder felt useless, and the prop grip felt very odd. I was on my starboard side, and it felt like the prop was partially churning air on the back side of a wave or something. it didn’t feel like my pedaling was very effective, but I was moving forward.

    I tried to make a turn to port and that failed as well. I was now being blown toward the entrance of the inlet, but because of my aggressive pedaling, I had moved further north toward the other rocky shore, so I stopped pedaling. I checked the GPS and was drifting 1.9 knots toward the north rocky shore. I calculated that my drift was 1 knot due to the wind, and .9 knots due to the tide current. I waited a bit and noted my drift direction on the GPS screen. I had been accustomed to doing this over the past few days, as I always wanted to make sure that If my drive leg ever failed while in the swells around all the rocks and reefs, that I knew my drift speed and direction. I had also developed a good feel for the tidal current from observing my speed on out and back runs up and down the inlet and in the channel. The drift vector on the GPS screen was pointing directly into the north rocky shore which wasn’t far away. I picked up my radio and called Clive who answered immediately. I told Clive that my rudder wasn’t working, the wind has knocked me down, and the wind was blowing me toward the coast. I asked him how much longer he thought he would be. He said he could get going in 5 minutes, but motoring down the inlet would take him about 20 minutes to reach me.

    I was becoming very concerned about my drift, so I started to back-pedal. The back pedaling moved me back toward the center of the inlet and I missed hitting the rocks. When I was blown deeper into the inlet, the waves and wind eased and I was able to power my way out of the knock-down and I proceeded back to the Marina. I tuned in the weather station right away on my radio and recorded that the wind was blowing 20 to 25 knots with seas at 3 to 4 meters.

    ————————–

    There are THREE problems here.
    The first is the roll-over during a 20 knot + wind. This position is very uncomfortable and if it happens with a port light open, the cockpit, or cabin or both will flood. The second problem is the constant turn to abeam the wind when drifting. This orientation is also very uncomfortable and my drift is exaggerated. The third problem is lose of rudder control and / or prop thrust when abeam a 20 knot + wind.

    I believe that the loss of rudder control is due to two factors:

    1. The wind is pressing against the slab sides of WiTHiN, and with the keel acting as a pivot point (I mean a pivot-point side to side, not fore-aft) in the water, the wind rolls WITHiN over and “pins” her onto her side. Rudder movements (with maximum prop thrust) isn’t enough to push the bow either upwind or, the stern downwind.

    2. When WiTHiN is rolled to 45 degrees on her side, the rudder is at an ineffective angle. A turn to upwind means that the rudder is acting like an airplane wing and trying to force the stern down into the water. A turn to downwind means the rudder is partially trying to force the stern up int the air.
    ————————–———
    Possible solutions:

    1. Add outriggers. 1 or 2 outriggers will counter the knock-down, but I believe the force of the wind on the flat sides of WiTHiN will still tend to pin her in that position. Perhaps the rudder still won’t have enough power to push the bow through the wind. Maybe a larger rudder in addition to the outriggers ?

    2. Larger rudder. I still think that a larger rudder at 45 degrees (or more) won’t be very effective, and that won’t solve the issue of the uncomfortable heeled position while drifting.

    3. Heavier and deeper keel. I think we have some structural limitations? I don’t like this idea because WiTHiN will be slower and heavier in the water.

    4. A fin on the bow with enough surface area to keep the bow weather cocked with the wind. This is a messy and non-standard solution.

    gk
  • 26 Comments to “Offshore sea trials”

    • George Simpson on April 4, 2010

      Hey dude. Worth talking to some of the owners of the longer “Woodvale Fours” rowing boats. They have dagger boards to countract a similar problem. Drop me a line if you need some contact details.

      Re the heavier keel and your reservations in relation to speed, remember the old saying, “in order to finish first, first you have to finish!”

    • Ray Girard on April 4, 2010

      Outriggers that are mounted to only touch the water just before the critical heel. They can be quite aerodynamic and the added windage would be minimal. Any effect would cause WITHiN to round up into the wind (you want that, don’t you?). An alternate would be to have them swing out from the back deck, like a beetle’s wings, with their pivot point just behind the CLR.
      Added stuff to go wrong but very useful in an ocean.

    • Steve Retz on April 4, 2010

      I was thinking of your problems and had a thought. Currently you have the rudder goes straight down. What if you let the rudder trail behind instead. By allowing the rudder to run almost straight back you still get a good bight on the water but you may not get the lift when the boat rocks to the side. Also what if you moved the keel forward? Can that be done? If the keel was moved forward the boat would always want to turn into the wind. So move the keel just enough forward so it has a tendency turn the boat into the wind. This would give you your control back. It’s clear you can’t power your way out of everthing but if you can turn the nose into the wind you can let the sea anckor drag out and wait it out till you can start padeling aagin when the weather clears up.

    • David Elderton on April 5, 2010

      Wow Greg, interesting what pops up when you are pushing the envelope. I think daggerboards might be the answer. I would not use outriggers, they would be easily damaged in a storm, add windage, and you may still not be able to turn. I suppose two adjustable daggerboards, one forward of the prop, one aft would be too much to retrofit into your design? How about an adjustable lee board? A long narrow board mounted to the side(s) of the boat, that could be pivoted from inside the cabin to suit conditions? It could be pivoted right up out of the water in calm seas. If you added two leeboards you could deploy only the windward one in a broach to minimize heel. I would also add a bit more weight in the keel and a larger rudder blade with a nice thick profile.

    • Bruce Bolster on April 5, 2010

      The problem here is lee-cocking, NOT weather cocking, and is similar to the situation in a keelboat when a large foresail overpowers the boat and the keel stall, causing a stable knockdown. You have to move the center of lateral resistance, forward relative to the center of effort, which is basically the “sail” that the side of within presents to the wind. At the moment the boat is too well balanced – these two points are too close together longitudinally. Since it would be a big project to move the main ballast keel/drive uni forward, a small keel at the FRONT of the boat should fix the problem, this will prevent the bow sliding off downwind. In my opinion the best option would be a moveable skeg similar to that seen on British-style kayaks, but located near the BOW of the boat. This would allow you to dial in size of the wetted surface according to conditions – you would want it all the way down in the conditions you encountered.

      don’t mess with outriggers, the will overstress the hull when you least want big forces applied to it – a tweak of the underwater empennage will fix this problem, and will add very little in the way of drag.

    • Thatcher Morse on April 5, 2010

      How about a forward skeg housing a adjustable daggerboard? It might slightly hinder turning response, but you’re not going to be running any slalom courses.
      On another note: you my have considered this already, but can you harness your pedle power to a generator? Mayby too much weight and still another gadget?
      Wishing you Fair Winds and Following Seas,
      Thatcher Morse

    • Skip Walker on April 5, 2010

      I just rectified this on canopus. we are rowing the missouri and mississippi and the gulf. kansas city to key west. Good luck man!

    • Skip Walker on April 5, 2010

      Bruce Bolster is correct-

    • Peter Raymond on April 5, 2010

      I just finished reading “A Pearl in the Storm”, written by the first woman to row alone across an ocean, Tori Murden McClure. The conditions you faced are fairly trivial compared to what she saw in the North Atlantic on her first attempt. You are not likely to go through a hurricane like she did, but she couldn’t make progress against a 20 knot wind either. I think though that being in control up to 30 knots would be a reasonable goal. That’s less than the capability of an ocean going sailboat, but probably acceptable for human power.

      Adding a skeg in the front will make the boat tend to turn into the wind, but that’s not the ticket if you are trying to pedal with the wind at your back. It will also tend to make the boat wander in normal travel. You could possibly end up in the arrow trying to fly backward situation.

      for one particular situation you might be able to balance the boat with weight trim. If you move the weight of your supplies and gear towards the stern, it’s similar to adding a rear skeg and the front is pushed harder by the wind because it’s sitting higher. This would be the trim to travel with the wind behind you. Reversing this might work for heading into the wind, but you can still have the stability problem I mentioned above.

      One of the problems you have is that the wind pushes on you full force, but the turning moment you can generate with the rudder is limited because your speed through the water is less than, for instance, a sailboat that could be going significantly faster. The force from the rudder is proportional to the square of your speed through the water, so at your relatively low speeds the force is significantly limited.

      A center board is recessed into the bottom of a hull. If you had one in front and one in back, you would have some potential to adjust both of them to let you chose between turning into, or away from the wind. If the center boards aren’t as deep as the keel, they will limit your side-slip, without heeling you as much. the centerboard trunk can be sealed so that you can raise and lower it from inside the boat, but still be waterproof. Talk to your marine architect about this. Just reducing the slip might alone make the boat easier to steer.

      A larger rudder is probably required though. I think significantly larger. I was kind of expecting you to have problems with the one you have once you got to the open ocean. Do you know how it works surfing down a wave?

      You should also look at the speed through the water and the front-to-back cord of the rudder and calculate the Reynolds number of the foil, or have someone do this. Many very good foils work very badly at very low Reynolds numbers. Rick Willoughby can certainly guide you in verifying that you are using an appropriate profile. Low Reynlds number also means that the foil will stall at smaller angles of attack, again limiting your ability to control the boat. you might also think about a skeg at the back with the rudder being a trim tab off the back. You could perhaps set up the flap/rudder as a high lift device similar to a two element wing sail.

      The only things I can think of to limit the tendency to heel are:

      1) Deeper keel
      2) More weight in the bulb
      3) A keel strut that is short front-to-back
      4) Cut off part of your roof line to reduce area.
      5) Smooth the profile of the roof to reduce drag in a cross wind
      6) Use a bulb that is wider than it is tall, so that it has the same weight, but less profile area in the side view.

    • Vince Fairleigh on April 5, 2010

      How about a small electric motor for emergencies? One more deep cycle battery and the solar panels can recharge them? Just a thought, and you would never use the motor for the trip unless you had to for your safety.

    • Sverker Fridqvist on April 5, 2010

      How about a (small) sail on the aft deck? This would keep WiTHiN pointed towards the wind (but would also create extra wind resistance). The issue is to shift the centres of forces, and doing that on the wind part might be easier than adding stuff below the waterline.

    • Martan Pernicka on April 5, 2010

      If das boat stop mooving, your rudder is indeed dead weighte; I was gooing to suggest “sail anchor” that could be deployed from the rear? but then I saw suggestion from Sverker above.
      Good idea.
      Again, this may be folded down when not needed? Size? 1 sq, feet is plenty? The only Goal: keep boat ailgned into the wind.

      Outriggers – will only add weight at this stage as it will not be integrated into theWithin’s design…
      Inflatable?
      One on each side and deployed only as needed? May be juste flat against the side as needed.
      Stored above flotation line when not used, will no drag when boat in motion.
      Design: a) two flat sheets, semi-rigid? with extendible contours. Will extend 9″ (+?) inches by hand pompe.
      Reverse air to store FLAT against the Within’s side.

      More brainstorming… i.e. thinking aloud while I am on it:
      Installation on the side, above the water line.
      b) two flat sheets are hinged on top together so openning is only on the bottom?
      c) Better: hinged on the bottom – the outrigger deploys out – and down towards the water.

      Bonne chance!

    • Martan Pernicka on April 5, 2010

      Lenght of these inflatable outriggers? 6feet?
      Try-it & erros-it 🙂

    • Martan Pernicka on April 5, 2010

      ^that was error-it of cours 😉

    • Jimmie Yarnell on April 5, 2010

      Good to have been able to exsperienc a seriouse situation during sea trials.
      I sailed Hobie cats for years and the length and depth of the rudder was always adquit because I had two,a deeper rudder is easy to create although comes with a penalty of drag.I like the rear sail idea to bring you up into the wind, unless it was sporatic and unpredictable.A deeper keel with reconsideration for the balance point and maybe closer consideration as to stored weight and its effect on the balance point.Maybe a close look at the weight above waterline or increasing balast in the keel. Pretty easy to give suggestions from this side of the keyboard compared to living the severiety of the problem real time.I’m sure you will get it solved. best to ya.

    • T on April 5, 2010

      How about a winged keel?

    • Dan McCaig on April 6, 2010

      Hey,
      Just a shot, how about some-sort of a water ballast? Pump in, and pump out? I am sure your team already has a solution… Good luck!

      –Dan–
      Sault Ste. Marie
      Ontario

    • Russell Moore on April 6, 2010

      Probably not practical at this stage, but combined with some of the other ideas, how about twin rudders as used on boats like the Volvo 70s? With two rudders splayed out at an angle, one is always pointing more or less straight down when heeled.
      It is obvious that the centre of effort of the deck, side on to the wind is close to the centre of lateral resistance of the hull underwater.
      Some use of adjustable fins fore and aft of the keel may be a way to experiment with this problem.
      Good luck, at least you have tried out the boat beforehand, unlike some who have gone straight offshore in calm conditions, only to see problems occur way out to sea when the weather has turned for the worse.

    • marc Ginisty on April 8, 2010

      Relax Greg, all the “ocean rowing” boats have the same problem than your craft. They go downwind very well ( some even don’t do that,ex: “virgin”) but not up wind. Too much windage for too little power. Some minimized the problem with a daguerboard to help balanced the lateral plane and help keep the bow in the wind. This way they can turn sideway and decide on what side to drift, at more or less 45 ° of the wind, easier to go up the wave and less healing. But they don’t go upwind in 20 knots of wind. they drift sideways.
      Outriggers would only add windage and waves induce resistance.
      Your trip is downwind for Hawaii, that is the good news..
      You are miles ahead in your preparation and understanding of the issues than many” ocean rowers” I know.
      Keep up the good work.

    • josh withe on April 12, 2010

      you could add more authority to the rudder by adding an end plate to it, just like winglets on airplanes make the wing more efficient by controlling the wash of air around the end of the wing, and end plate on the rudder would give you a bigger effect with out a bigger rudder.
      combined with a dagger board in the front, and also a lee board (you only need one as you won’t be heeling and tacking like a sailboat) you would have a much better chance of maintaining control. The more options, including a small stay sail, you give your self, the better. Good luck.

    • Bill Serjeant on April 12, 2010

      I would suggest your have two adjustable daggerboards, one near the bow and the other near the stern. These would enable you to trim the boat on any course. Keep the existing rudder for use in low wind speeds; otherwise steer the boat with the daggerboards. When riding to your sea anchor, deploy the forward daggerboard and if necessary rig a small riding sail near the stern. When running before the seas, use the stern daggerboard.

      If you need more stability, fit inflatable tubes around the gunwales, as with Klepper kayaks.

      You could consider the addition of a rudder similar to the ‘twist and stow’ rudder on Hobie Mirage Adventure Island Trimarans, but I’m not so keen on the idea, because there are parts that may fail.

      http://www.hobiecat.com/media/video/video_features.html

      Bill

    • Mike Burgess on April 13, 2010

      Adding a sail will do no good at all. Anytime the wind would blow he would be dead in the water and waiting till it died enough to continue along. Never get a record that way. Put the drive system in the front and pull the boat along. No need for longer rudder/daggerboard and less wetted resistance. Use of a rudder IMO is overkill if this was to be the case. Just turn the drive system and have even less wetted resistance (like a trolling motor).With all boats it is through trial and error to get things nearly right (never perfect). Good luck

    • Leonel Murguia on April 14, 2010

      hello
      I think you should reduce the lateral area of the keel.
      Without changing its weight (not add more weight)
      The weight of the keel must be vertically flattened
      All the keel must have minimum lateral area
      The keel post must be a steel rod, not a tube … and must be flexible… the fairing must be minimal
      Same thing with the prop leg.
      The boat most be able to roll with minimal dinamic resistance.

      cordialy
      Leonel Murguia
      Research and developmet of boats autopilots
      eTIMON
      QC Canada

    • Leonel Murguia on April 14, 2010

      Hello Roz!
      I admire your adventures. During your travels, I watched several times a day to see your progress and read your comments. I would have liked to be in your boat for row while you were sleeping.
      My sincere congratulations
      Leonel Murguia from Quebec, Canada

    • brisy on April 14, 2010

      hello how interesting to read the various proposals to solve the problem…certainly a mix of both methods could work acting as well under the water line (two rudders as many sailing boats have now to get one operating vertically)and above some vertical board or sail could also help the bow to come into the wind…and what about the long keels the passengers boat have to stop the roll movement at sea?i’m sur you will mange that trouble with your staff and eager to read what you found! as the guy above said it’s so easy from this side
      friendly
      marc

    • David Webb on April 15, 2010

      Hi Greg,
      as many of the comments above suggest, a combination of a small sail and one or two daggerboards can probably solve the problem. One suggestion that has not been made so far is to have a daggerboard that penetrates the full depth of the hull at the stern and a long board that when down will turn Within downwind and when up will act as a sail and turn the bow in to the wind. This would provide the control that you need and options on direction that the bow points. When in the mid position it would leave the boat unchanged.
      I hope that this suggestion helps.
      All the best with the project.
      David.


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