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Thread: Boat trim - fore and aft.

  1. #1
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    Default Boat trim - fore and aft.

    Morning folks.
    The ice has now turned back to water here in Sweden and trips are being planned...
    Would one of you more knowledgable people be able to help me with boat trim?

    Is it best to have a slightly bow down attitude or stern down when loaded?

    With me on my own and no kit, the boat is about level. But with camping gear in, which bias is best?
    Cheers
    Paul
    Looking for the end of the rainbow

  2. #2
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    Depends what conditions your paddling in

    If the bow is slightly heavier it is less likely to be blown off by the wind which can be helpful if you're trying to paddle into a headwind

    This can be less desirable in other conditions when you would like the boat to turn more easily

    You might also consider how you load and sit in the boat for example if you sit in the Stern and load all your gear in the front the boat may track likely straighter. If you sit just behind the yolk and have your gear just in front of the yolk with the ends empty the boat may turn more easily

    Sent from my SM-G950F using Tapatalk

  3. #3
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    Quote Originally Posted by sonflowerinwales View Post
    Morning folks.
    The ice has now turned back to water here in Sweden and trips are being planned...
    Would one of you more knowledgable people be able to help me with boat trim?

    Is it best to have a slightly bow down attitude or stern down when loaded?

    With me on my own and no kit, the boat is about level. But with camping gear in, which bias is best?
    Cheers
    Paul
    The general idea is to trim your boat with an even keel when there is no wind; trim your boat stern heavy when there is wind coming from a direction more or less behind you; and trim your boat bow heavy when you have the wind against you.

    While all this seems fairly simple, it gets more complicated when we have to decide how much we should trim the canoe.
    How much trim we need, depends on the wind direction, the wind force, the design of the canoe and the speed that you (can) paddle. The faster you (can) paddle, the more course stable your bow will relatively become, so the less you will have to trim bow heavy. With enough speed, an even keel will often be the best choice when paddling against the wind, where a bow heavy trim would in fact make course keeping more difficult then. You will just have to try for your own situations to find out what gives the best results.

    Dirk Barends

  4. #4
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    Default

    Thanks guys.
    Water conditions here go from glassy calm to half metre swell.
    And from no wind to stay at home wind levels.
    I sit in the centre of the boat, luggage and crap at the ends.
    So moving stuff around en-route won't be too difficult.
    I will try bow down into the wind first, that makes most sense to me.
    Stay dry guys.
    Paul
    Looking for the end of the rainbow

  5. #5
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    As above, really. The end facing the wind should be slightly heavier.

    On open water, eg Scottish lochs, with camping gear, I tend to be quite heavily laden. I try to adopt a neutral trim and depending on conditions, central bags will likely be on a leash with front and rear bags tied in. One item, maybe a 5L water can, or a similar weight other item, will just be clipped into place, and I can move this from end to end as required.

    Don't forget that also, your body weight is one of your most useful tools for moving around, especially if the canoe is less heavily laden. For day paddling on slow rivers and sheltered waters, I am normally just slightly bow light. Leaning forward is then often enough to weight the bows enough in moderate winds.


    There is another factor that comes into play, most especially noticeable when the wind and waves are roughly behind you, but maybe at a slight angle. If your stern is then TOO heavy, I find it can dig into waves and get pushed around. The same happens in a headwind/waves, but as you see them coming, its easier to face them at the angle you want to, and be ready for it. This is another reason why I try for a basically neutral trim with a movable weight.


    You're not kidding when you say that Scandinavian lakes can change from dead calm to big swell in minutes. This happened to us on Femunden, a huge lake. Perfect calm, dead still, so we committed to going for a 2 hour paddle in late evening to make camp, to avoid stronger winds forecast the next day. Within 10 minutes of leaving the calm beach, we were fighting wind and waves that were big enough to have us questioning if we should abandon the trip, but luckily they dropped just enough to continue.
    Paddler,blogger,camper,pyromaniac: Blog: Wilderness is a State of Mind

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  6. #6
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    Afternoon
    Weighed all my kit this morning.
    4kg x 1
    3kg x 3
    So I can tie one at each end and two close to me in the middle so they can be moved as needed.
    On a side note, the ice is still too thick to launch from the shore!
    I tried....
    Paul
    Looking for the end of the rainbow

  7. #7
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    Hello Paul. I agree with all of the advice you have received and I enjoyed reading it. I wanted to add a few comments...

    You did not mention the type of canoe that you paddle and the type of paddle you do. Those details might be helpful.

    To answer your basic question I think it is better to be slightly bow heavy. I have owned many solo canoes over the years and the ones that come with fixed seats will always be set up a bit light in the bow, presumably so they will be trimmed properly when a pack is added. I've met a lot of canoes and they all seem to like a load in their tummy (in my case I take a dog). I think you will find that if the bow gets too heavy then the boat gets "tail happy" and hard to control. But a little bit bow heavy makes the boat responsive and is probably more efficient since the drag of the boat is partly due to the wake coming off the stern so when you go a bit bow down you lighten the stern a bit.

    All that said, in your specific case I would discourage you from putting packs at the ends since the boat will turn more easily if you keep the weight centralized plus you minimize the impact of the weight of the packs on trim when you keep them close to the middle of the boat. Plus...your total load sounds just admirably light at 13 kg (my dog is 25 kg or a bit more and she sits right in front of me) so I think it's likely that you should just put all of your small packs right in front of you for best performance and trim.

    Cheers Paul,

    Tom

  8. #8
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    I'm not sure that I have ever experienced the wind behind me. What is this phenomenon you all speak of :-)

  9. #9
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    Default Trim

    Hi daytripper
    The boat I built is a Trapper 15-35, full thread here http://www.songofthepaddle.co.uk/for...212#post649212
    Luckily the ice has now thawed close to my regular launch site, might just give your idea a go this weekend.
    Might even be able to get some pictures...
    Cheers
    Paul
    Looking for the end of the rainbow

  10. #10
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    I was working on a couple of videos, one of which was about Trim, until I was struck down with a mystery illness ("struck down" is probably a bit strong, I'm basically fine, but trying to minimise the time spent out of sprinting distance of modern plumbing!). So I'll throw the basic concepts here, although I'm going to ignore wind, I was saving that for another video and hadn't started writing the script. Videos will follow, if the doctor ever figures out what's wrong with me.

    A flat trimmed boat moving forward through the water is pushing it's bow into new undisturbed water, while the stern is sitting in the shadow of the bow, which means that most of a canoe's drag is focused on the front of the boat. With the drag focused at the front, the bow is being slowed down more than the stern, and effectively the stern is constantly trying to overtake the bow. Our boats don't want to go in a straight line, they want to turn.

    It's an odd idea, that our canoe doesn't want to go pointy end first in our direction of travel. I say it's odd, but anyone who's paddled knows that if you stop paddling, your boat will turn, often not really changing it's direction of travel, just the direction it's pointing in.

    Now trim is an amazingly powerful thing, but there aren't any miracles here, our boat is always going to be directionally unstable, it's always going to turn when you stop paddling, but we can reduce that turning effect, and even if that's just by 10%, that's 10% less steering and 10% more forward power we can apply.

    If we trim a little stern heavy it slightly increases the drag at the stern and slightly reduces the drag at the bow shifting the focus of the boat's drag back a little, and so the turning effect is reduced. Add to that the stern being deeper in the water acts a bit like a rudder set to straight ahead, resisting slightly any sideways movement, and (hopefully) we can see it's a little easier to forward paddle with stern heavy trim, just because there's less steering to do to keep in a straight line.

    Now let's not go mad here, whatever we do the front of the boat has to push water out of the way, and that's easiest to do with the lovely pointy bit at the front still in the water. An inch or two higher in the bow than the stern is all it needs, and it's very easy to over do it, go too far and you change the shape of the water line so you're pushing a blunt bow through the water and that negates any gains you make from having to do less steering.

    Bow heavy trim is extremely useful however. Most of the time when turning our boat we want to keep our momentum, so we just paddle round the turn, steering with our choice of stroke, but if momentum doesn't matter, why not use drag. We paddle along, just a little stern heavy (remember, not too much, just an inch or two difference), then when we want to turn, give the boat just a hint of the direction we want to go with our last forward stroke, then we throw our weight forwards onto our knees to slam the bow as deep as we can into the water, stalling it, while the newly lifted and loosened stern is free to swing snappily round the turn, a couple of tries and effortless 180s become easy (I say effortless, they look effortless from the outside, but I quite often get cramp in my legs from repeatedly throwing my weight around like that). Probably best to lean the boat into the turn too, at least for the first few tries, those turns can be a bit quick and the boat might spit you out.

    I hope that makes sense, the video script is about 5 times longer and goes in baby steps making it easier to understand, but in writing, without distracting video and diagrams, it gets a bit tl;dr, so I've cut it to it's bones (and it's still too long for a sensible forum post).

    If you're interested I talk about something very closely related to those flat water stalling turns in a video about breaking out (almost identical turns, just done in a more complex environment), it's on my youtube channel.
    Last edited by saarlak; 30th-March-2019 at 03:00 PM.
    The only thing you have to fear is Mergatroid the vengeful, man eating bear.
    (and my youtube channel)

  11. #11
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    Quote Originally Posted by bobt View Post
    I'm not sure that I have ever experienced the wind behind me. What is this phenomenon you all speak of :-)
    You need a Swift Osprey solo canoe; the Osprey is exceptionally fussy and hard to control in strong tailwinds so if you get one you'll be guaranteed to have tailwinds whenever you paddle.

  12. #12
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    Quote Originally Posted by sonflowerinwales View Post
    Hi daytripper
    The boat I built is a Trapper 15-35, full thread here http://www.songofthepaddle.co.uk/for...212#post649212
    Luckily the ice has now thawed close to my regular launch site, might just give your idea a go this weekend.
    Might even be able to get some pictures...
    Cheers
    Paul
    That's a fine looking canoe. I was curious to see how close your solo seat is to the center of the boat. If you paddle solo from the front seat facing backwards then you are going to be bow light unless you get some weight in front of you. I was also curious whether you sit or kneel since kneeling gives more room for gear directly in front of you but you appear to have plenty of room for your light gear load. Finally, if you race canoes or often experience strong tailwinds then there's another concept called the Peripatetic Pivot Point that you may want to know absolutely it. The pivot point of your boat shifts forward the faster you go...and this is one reason that a boat can become uncontrollable in strong tailwinds. So if you go fast that suggests that your trim should be biased a bit more stern heavy.

    https://clydewinter.wordpress.com/20...c-pivot-point/

    I like the look of the motorcycle in your profile. What is it?

  13. #13
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    Default Bow heavy, tomorrow will tell

    Hi there

    @saariac - will have a look at your youtube later

    @daytripper
    Seat position. There was a lot of thinky stuff to determine the final position. The boat is designed for two seats, but as it will only be ever used with me on board so I went for a single (home design and made) seat. I looked at plenty of pictures, plans and with some scaling, best guess and some luck, the forward seat edge is just aft of the centreline.
    I normally sit with legs out in front, but if I'm feeling "proper" then I kneel, but I do find this a little uncomfortable after a while.
    So, my arse is behind the centre point, legs in front.
    Plenty of room for loads more kit if I wanted, but being on my own, travel light.
    Bike. A 1963 Honda CB72 250cc, built by my own fair hand from a box of bits many years ago. Roadworthy and should have its first outing at Easter.

    Tomorrow I will get some more pictures.

    Cheers
    Paul
    Looking for the end of the rainbow

  14. #14
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    Ermmm?..Boat trim, depending upon fore or aft attitude....

    Always allow for some 210lbs or so (15 stone ) of astern paddler, whatever the weather!

    Or in this case, in somewhat 'mid-Oxfordshire arid conditions' () allow for the ice melt and the reduction in chilled fizz extraction, as the bow slowly raises!

    I hope this may be of help, but very much doubt it!-
    Keep yer paddles wet, and powder dry....

    MB

    `..`. ><(((( ((>
    `..`..`. ><((((>

  15. #15
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    Note that the magazine is cleverly stowed amidships thereby ensuring that intense triple-A fire will not affect the boat's trim...



  16. #16
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    Hmmm - that magazine appears to neglect the lessons of the Battle of Jutland. I would have thought the crew of the Royal Navy canoe adjacent would have spotted that - unless the White Ensign means we have a member of the Royal Yacht Squadron among us?

  17. #17
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    Where did you get that hat?

    Way better than a Tilley.
    This post may vanish at any moment.

  18. #18
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    Quote Originally Posted by Chris_B View Post
    Hmmm - that magazine appears to neglect the lessons of the Battle of Jutland. I would have thought the crew of the Royal Navy canoe adjacent would have spotted that - unless the White Ensign means we have a member of the Royal Yacht Squadron among us?
    We do Sir!..and she paddles frequently amongst us all, with with her trusted crew....
    It's Henley or bust!

    Now before I'm accused of hi-jacking this post ( my apologies already sonflowerinwales)....let's get back to your original question about boat trim, be it bow down or stern down when loaded....

    The addition of a small child upfront often helps!
    Meet Rory, aged 4 at the time...

    Who stole the whole show! (and I'll put that down to damned good parenting....as seen frequently on this forum! )
    Last edited by Bonarmbj; 5th-April-2019 at 01:02 AM.
    Keep yer paddles wet, and powder dry....

    MB

    `..`. ><(((( ((>
    `..`..`. ><((((>

  19. #19
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    Hey sonflowerinwales, how about a few more pics of your Honda?

    My older brother had a 1966 Honda 450 and I had a 1972 CL350 when I was 16 years old and less than 60 kg. At that time one was supposed to be 18 to ride anything over 150cc so I felt like the fastest thing on the road with that 350.

  20. #20
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    Canoe trim is best to change as needed. If you trim neutral then your body position will determine your trim. [VIDEO]https://youtu.be/p2XnSrYUUUo[/VIDEO this’s critical when back paddling in big currents.
    Dr. Joe
    Electric Hospital
    Coos Bay Or
    http://electrichospital.com

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