RE: [Paddlewise] A question of trim

"Carey Parks" <carey_at_jimparksfamily.com> wrote.

<snip>
>>>>>>>Day 2, I drank a couple gallons of water by then, and packed
everything where it was the day before. The empty water containers were
ahead of my foot pegs in the cockpit where they had been before, but full of
water. This day I couldn't get the boat to go straight. Anytime I put any
speen on, I mean like three mpg or so, the bow would fall off to one side or
the other.
Quite frustrating. I was glad when we stopped for the day.

Day 3, suspecting that I was loaded too heavy aft, and having consumed more
water, I put what water I had left forward, determined to prevent the
problem I had the day before. And that I did. I couldn't get the boat to
turn without a LOT of effort on my part. It was obvious I had too much
weight forward this time.

I still couldn't tell you by looking when I have the boat loaded properly.
But I can tell you by paddling it when I've got it wrong!<<<<<<<<<<


Carey, are you sure you are remembering this right? What you described would
likely work just the opposite way. More weight in the bow tend to make a
boat squirrelly and increases weatherhelm. More weight in the back tends to
make for stiffer tracking and less weatherhelm (or even a little lee helm if
overdone). 

There is a long discussion in our "Owners" manual on our website about when
and in what conditions bow or stern heavy trim is desirable, so those who
are interested can read that (it starts about 1/5 of the way into the
manual). I won't repeat myself here. 

To answer the original question, most would consider proper trim to be the
trim at which the boat is most efficient. For a kayak that would be when the
non-rockered area of the bottom (in the middle) is level (front to back)
when the kayak is floating at rest. A simple level placed on the hull in
front of the seat can probably tell you if the hull is level. When we
designed the original Mariner we did a lot of math (Simpson's rule springs
to mind) in order to figure out where the center of gravity of the paddler
plus boat should be for level trim. That allowed us to put the seating
position and cockpit in place before getting the boat wet. After that we
took a shortcut and just sat in the plug hull in the water with a
carpenter's level between our knees to determine the seating position and
cockpit placement. 

That said, for your Sea Lion you might find that while it slows the top
speed slightly (and possibly makes paddling at cruising speed not quite as
efficient) and makes for more pounding in head seas moving the seat further
back as you did (a stern heavy trim) will likely improve the handling of
your boat in sidewinds and following seas (less weatherhem and reduce
broaching). It will also make the kayak a little stiffer tracking (and
harder to turn up into a high wind when it is unladen). A side benefit will
be to make it easier to get in and out of the cockpit. Lay-back rolls may
not be as easy if the seatback is too close to the rear of the cockpit.

Most kayaks become bow heavy when loaded with gear. Think of the kayak like
a teeter-totter with the fulcum about in your crotch. Since your legs stick
out forward much more than your back does to the rear, gear going into the
front is further out the teeter-totter from the fulcrum so it takes less to
keep it level. With a full gear load it is very hard to put too much of the
weight in the stern. All water and the densest gear bags should all go in to
the stern.

Matt Broze
www.marinerkayaks.com  
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