Pacific Rowboat

Discussion in 'Boat Design' started by Eric Sponberg, Oct 8, 2015.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    It does occur to me that the radar signature should be maximized, so it becomes easier to find, or for the purpose of collision avoidance. Maybe have some kind of radar detector that tells you there is shipping in the vicinity, especially useful if asleep.
     
  2. Remmlinger
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    Remmlinger engineer

    Thanks Eric for the link to this ingenious design.
    The quietness of the motion is a big point and I will consider it for my own plans.
    Thanks for sharing
    Uli
     
  3. Eric Sponberg
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    Eric Sponberg Senior Member

    At the moment, the solar panels are not aimable, but that could change. One thing I thought of at one point was to put solar panels on the sides of the cabins as well as the top, so that you could pick up power very early and very late in the day, but the intensity of light is not that strong at those times, being filtered through greater "thickness" of atmosphere, so for now we have just the panels on top, and quite a lot of power, actually.

    In ocean rowing circles, you are judged very severely for having any kind of canvas overhead because, it is claimed, you could use it for a sail that would give you undue assistance to your rowing. We went through a lot of conniptions to get the proportions and features of this boat just right that would pass muster with the ocean rowing enthusiasts. You see in this design we have a hard top over the cockpit which is built onto the back of the front cabin and extends to a panel that slopes down to the top of the aft cabin. In the sloping panel, there are three windows, and the center window opens as a hatch or lift-out panel (latter is easier/cheaper to build). We do have side canvas to close off the sides of the cockpit, which apparently is allowed, so that Jacob can close off one side or both to keep out wind and spray from the cockpit. I described this as a "back porch" feature with one canvas up on the windward side, so that you are still open to the leeward side. He quite liked that description. This is very important, to my mind--you expend a lot of energy just keeping warm on the open ocean, and protections from the sun, rain, and spray are essential.

    Eric
     
  4. Eric Sponberg
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    Eric Sponberg Senior Member

    We do have a radar reflector on board--it is a Plastimo tubular radar reflector that is mounted on the back side of the wind generator pole. Jacob will also have VHF with AIS installed.

    Eric
     
  5. Oleboynow

    Oleboynow Previous Member

    I do like the design, have not read thread yet
    I thought of doing same for Voyage NZ Towards Au
    But in alu as I can not work with that sticky stuff
     
  6. Rurudyne
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    Rurudyne Senior Member

    I really like the design and wish the guy well.

    That said, I've a strong silly streak and so now something totally random.

    A new toy for the rich.

    A virtual reality rowboat that controls the azipod thrusters on your multi-million dollar yacht. Let your family go in comfort as you "row" your way from here to there. With advanced features that account for the effect of wind and tides on your rowboat, positioning your yacht exactly where you would otherwise be. Environmental controls let you (and you alone) enjoy heat and humidity that exactly mimics where you are while state of the gimbal simulate the motion of a small boat on the open ocean and AI systems governing oar resistance make your backache and muscles feel like you were really roughing it.
     
  7. FoveauxSailor
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    FoveauxSailor Junior Member

    Hello Gentlemen

    When Jim Shekhdar was preparing his boat for his attempt to row to Africa via Cape Horn from Bluff, New Zealand, I spent a lot of time assisting him here to complete preparations.

    He stayed with us for several weeks and was an inspirational guest with a huge charisma, he was a real tough guy both mentally and physically. I always considered that the voyage he'd planned was very very tough, and unlikely to end well, but if anyone could have done it, he might have been the man.

    I spent some weeks working on his boat, and conducting sea trials etc. I considered his boat overly dependent on "systems" for watermaking, communication, navigation etc, and I think this is an aspect to consider very carefully. Most of these modern systems are dependent on a few critical points and if for example your energy generation systems start to break down you are going to be in the **** - and that can be from something as simple as a poorly installed/designed/considered electrical connection methodology.

    I would be very careful about analyzing where one small failure might lead. On Jim's boat the "mast" for the wind generator was very vulnerable (the mast design for your boat look similar) and these sorts of electrical systems are very hard to keep going in a marine environment. If it is "smashed" what else will it damage ??

    You will also have to watch the builders like a hawk, its not their life's blood that's at stake, and on Jim's boat they had taken many of the shortcuts that professionals do (not with any malice), and made things just about impossible to fix on land, let alone at sea with limited resources. This applied to basic things like tank construction through to the fittings chosen.

    Cheers
    Foster
     
  8. Eric Sponberg
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    Eric Sponberg Senior Member

    Hi Foster,

    Your points are well taken, and we have tried to think through various scenarios that might lead to failures and "dire straits." Jacob's discussions with builders have included a request to participate with the builders in building the boat, and most have proven favorable to the idea. So he'll be there to make sure the boat fits him like a glove and that everything is reachable and fixable. He'll also spend some time living on the boat and rowing for some shorter passages to make sure the boat is ready for the long trip.

    Eric
     
  9. RHP
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    RHP Senior Member

    Eric many thanks for sharing this design. I've been fascinated by ocean rowing for years and despite being on the sunny side of 50 still harbour the desire to row an ocean. I follow the races and have read many books, including Jim Shekdhar's. If I be so bold as to make some observations:

    1. The keel stands out as way deeper than other boats. Is this for directional stability (some boats use dagger boards), self righting (does she carry less water ballast than other designs) or.... ?
    2. How does the wetted area compare with the 'standard' pairs design as a consequence and drag created by the keel?
    3. You have a reduced beam, is this to improve rowing and what is the effect on open sea stability? Is the keel needed to offset etc..?
    4. The superstructure is unconventional as you mention. One of my concerns of closing the cockpit is claustrophobia after time. ie the need to stand up and walk 3 paces, or stand and shout at the devil. Whilst I completely agree with your explanation of weather protection and the very real issue of sun protection v's the fear of sail power, I don't have a solution. I want the protection but need open space and agree that boats must not have any structure that affords a forward drive other than by oar. I am horrified by Charlie Pitcher's boat.
    5. You place the accommodation cabin forward. Surely in a narrow boat that space will pitch most? I would prefer to be aft.
    6. I take on board Foster's points on reliability. A belt and braces approach adds weight and possible complexity however on the other hand one rogue wave could end you dream so I guess everything is a compromise. Fuel cell and a spare water maker come to mind.

    It would be great if ocean rowers provided ongoing boat performance and design improvement feedback as I imagine many issues are repeat occurrences however I'm equally sure once they finish the race they get out and run away!

    Many thanks once again Eric, great stuff.
    Richard
     
  10. tspeer
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    tspeer Senior Member

    Needs wing mirrors! I've found them to be really useful on my wherry.
     
  11. Eric Sponberg
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    Eric Sponberg Senior Member

    Hi Richard,

    Thanks for all your questions, I'll take them in order:

    1. The keel is deeper than other boats because I think other boats don't have enough keel. It is primarily for directional stability, weatherliness, and gives the option of adding more fixed ballast should we discover the need as Jacob shakes her down.

    2. Of course there is more wetted surface, more than comparable boats. And while that may add to the load on each stroke, I surmise that one makes up for it by staying on course much more easily. This boat will wander less in a seaway than more shallow boats.

    3. We studied boat proportions considerably in our parametric study at the beginning of the design process, looking in detail at what I considered the best 13 custom and traditional designs in the field. We looked at length-to-beam ratio and weight per square foot of waterplane area (estimated), primarily, as well as overall arrangement, degree of human protection, ergonomics, etc. The lengths of boats varied from 15.50' to 35'. Beam varied from 4.59' to 6.23'. L/B ratio varied from 2.818 to 7.000. We had weights on only 6 boats (offshore rowers and the people who write about them are notoriously stingy with good technical data). Of those weights that we knew, they varied from 700 lbs. to 3,500 lbs., and I could not say if those are "dry lightship" weights or "full load" weights. My final proportions of 28' x 5' are very close to the straight trend lines lines through the data. The weight ratio was taken as (vessel weight)/(LxBx0.65), and these values were all over the chart--you could not pick a good trend line to find average values. So, with anything, this is all a bit of a guess, and that becomes the art in boat design. Also, boat dimensions and proportions are influenced most certainly by oar position and oarlock location, as well as heel, knee, and seat height--all these factors have to be taken into account. As I said earlier, I took dimensions of Jacob while he was here in my office, and he admitted to being shorter in the torso and longer in the leg than the average person. I could certainly see this in the drawings as I designed around his particular human frame.

    4. I know exactly what you mean about being able to stand up. We took that into account. In the cockpit, there is a 2' x 2' foot well, and if you stand up there and open the window hatch in the hardtop above, you can stand up full height and have a good look around. Scream if you want to! In the forward cabin, same thing. The aft section of the forward cabin is another 2' x 2' foot well, and standing up here puts your head in the clear plastic dome above. So I agree, standing up is important, as is being able to lie down full length for the best rest. Another feature that we have is that there is a folding cover over the foot well in the forward cabin, and Jacob will have a collapsible seat to put over this so that he can sit up and face forward when inside the boat, and look out the forward facing window. These features, together with the dome above and the wrap-over side windows, will help to dispel claustrophobia. Good points, and I'm glad you brought it up.

    5. I will dispute whether you will feel pitching more in the forward cabin versus the after cabin. The pitching center is the center of flotation (LCF) of the waterplane, and in double-ended boats, like this one, the LCF is only slightly aft of amidships. This will be a small boat on a big ocean, and the motion is going to be bodily, not so much as pitching only, or rolling only, or yawing only. It's actually going to be all six degrees of motion all at once. The sleeping area is to be in the main forward cabin, and as I said earlier, for a number of other reasons, we decided that the bigger cabin, where you would sleep, should be forward of the cockpit, not aft. Your measure of comfort (or discomfort!) while pitching and laying prone in the boat is dependent on the position of your head (and your inner ear canals) in relation to the LCF. The LCF on the Pacific Rowboat is at about station 14.5' (aft from the stem). If you lay down in the forward cabin with your head over the panel over the foot well so that you're as close as possible to the pitching center, your head will be at about station 12', just 2.5' from the LCF and pitching center. If you lay down in the aft cabin, again with your head forward to be closer to the LCF, first you'll be over the toilet, and that's a questionable proposition, but more importantly, your head will be at about station 20', fully 5.5' away from the LCF. So, you'll actual feel pitching more in this boat in the aft cabin than in the forward cabin. Your sense of pitching accelerations will be more than twice as much in the after cabin as in the forward cabin because your head would be more than twice the distance away from the LCF. The magnitude of accelerations varies linearly based on distance from the pitching center. So in this boat, the best position for the main cabin and for sleeping is, in fact, in the forward cabin. That's a very good question.

    6. You certainly have to plan for failures, and I believe Jacob will have a hand-operated watermaker on board as well as the built-in unit. You can only go so far with back-ups, however: do you have back-ups for your back-ups that back-up your back-ups? If you go too far with that reasoning, there won't be any room left for the rower! Also, on this design there is never a question of IF the boat is going to get hit by a rogue wave, rather the question is WHEN it's hit by a rogue wave, what happens? The scariest scenario is that the boat rolls over and does not come back up. This boat is very unstable upside down, so it will roll over quickly.

    Also, one thing that we have on this boat that I doubt you'll find on other boats is a dedicated ventilation system for each cabin. There is an air inlet and air outlet in the main bulkheads of each cabin, and these have gate valves inside the cabins against the bulkhead, and covers and dampers (exhaust damper only) on the outside of the bulkheads. Air comes naturally into the cabin from the air inlet duct, but is drawn out from the far end of the cabin from the air exhaust duct and in-line fan. From the inlet gate valves there are pipes that bring air to the bottom of the foot well in each cabin, and WHEN the boat is knocked on its side or upside down, the open end of the pipe is above the flotation waterline. Likewise for the air exhaust, the open end of the exhaust duct, at the far end of each cabin, will be above the waterline when the boat is knocked sideways or upside down. So we have spent plenty of time thinking through the systems and imagining what will happen when the boat capsizes. I attach the ventilation system drawing so that you can see what I describe. Note the position of the upside-down waterline across the profile view and across the sections.

    The one thing that I have found about ocean rowers is that they are not designers, because if they were, they would be sure to tell the full story about boat dimensions and performance. We designers can tell an awful lot about potential performance based on dimensions and proportions, and we can confirm or deny design suppositions if we also know the rower's experiences about life on board the boat. Sadly, the pertinent dimensions are usually lacking, so we designers are left with only part of the picture when it comes to stretching the design envelope.

    Eric
     

    Attached Files:

  12. Eric Sponberg
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    Eric Sponberg Senior Member

    Hi Tom,

    We thought of that! I attach an image of some sample sections which show the wing mirrors on the bulkhead at station 19, the aft cabin bulkhead. These also show a section through the rowing position.

    Eric
     

    Attached Files:

  13. W9GFO
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    W9GFO Senior Member

    I think it would be of great value to have the ability to take a few steps while upright. Being confined to standing erect in only two positions would wear on my sanity.

    Instead of a canvas top that could be used for catching the wind, why not making a sliding hardtop? Something similar to what you see on the Vendee Globe boats.
     
  14. Eric Sponberg
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    Eric Sponberg Senior Member

    Hi W9GFO--It's really hard to have walking space on an ocean going rowboat. Interior protection, in my opinion, in the form of protective cabins is more important than going on a walkabout. The cockpit is only 6' long, 2' of which is taken up by the foot well, so that leaves 4' of walking length. that's not a long walk--it would be a stretching stance and that's about all.

    One could make a sliding hardtop, but that would complicate the structure and add significantly to cost. This is already an expensive boat, and we have had to make compromises. For example, I designed the forward-most and after-most form-fitting hatches to be hinged. But because of the house curvatures, such hinges would have to be made as custom interior offset hinges, a very expensive proposition, according to some of the builders we've approached. The cheaper solution is to make them lift-out hatches with no hinges but with a tether--that may be not as ideal or elegant, but it is much less expensive.

    Eric
     

  15. W9GFO
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    W9GFO Senior Member

    Hi Eric, I didn't mean to suggest sacrificing interior protection for walking space. A 6' x 5' open space with nothing overhead would be of immense value to me just for mental health reasons. Does not matter that the horizontal surfaces are not on the same plane.

    The extra expense to make the hard cockpit cover sliding is a consideration. I think I'd rather have nothing vs. something that cannot be moved out of the way. All the ocean row boats that I have seen have space to move around like I describe. Not that I've seen them all of course.

    If Jacob has spent much time alone offshore then I guess he would know best, if he hasn't, I hope he can imagine what it would be like not being able to stand in an otherwise very open cockpit - for several months. I think I'd be reaching for the sawzall within a couple weeks.

    If the hard top were replaced with canvas, while retaining the tubular supports then the canvas is only a flat panel. If it is made to slide back and forth something akin to a canvas sunroof, then that should not raise concern to those who might accuse it of being a sail.

    [​IMG]
     
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