Compasses^

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tommfuller
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Compasses^

Post by tommfuller » Wed Apr 04, 2007 2:18 pm

Looking for some advice, as I'm looking for a compass to stick on my Capella - it has the hole for a Silva 70P so I was hoping you folks could let me know how you've got on with that option. It looks to me like it might be a little far away for general use. Also, is it likely to get scratched or bashed during transit if it's stuck there?

The alternative seems to be a Silva 58F compass attached to the decklines (or I just stick with my hillwalking type compass!).

Cheers,

Tom.

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Jim
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Post by Jim » Wed Apr 04, 2007 2:44 pm

Normal thing is to have a compass with big numbers reasonably well down the boat so it is in normal line of sight and you don't have to look down at it (mine apparantly is a bit close), and have your hillwalking one handy in case you need to do mapwork in the boat (unlikely I do most the night before and just keep tabs on where I am in the day).

I use a 70UN which is easily removed for transit.

The idea generally is to have the bearings sorted in advance (if you need them) and then to be able to sight through the bow of the boat and compass as you paddle, so the compass up front is only ever used for paddling on a bearing.

I could hijack the thread for an interesting debate, but I won't - yet!

Jim

Owen
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Post by Owen » Wed Apr 04, 2007 3:02 pm

The silva 70p and 58f can be a bit hard to read as the numbers are quite small.
I use a silva 85 which was once on a round hatch cover, the cover perished long ago. So, I've now mounted it on a plastic plate, cut from an old chopping board, four bungees hold it in place.
For night paddling I use a fishing float light (like a very small chemical lightstick) taped to the top of the compass dome.

Peter M
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Post by Peter M » Wed Apr 04, 2007 3:18 pm

I use the Silva 70p, mostly to fill the performed recess that I keep looking at in the bow of my boat. My reading eye sight is completely shot from staring at CAD screens all day. I can still read the larger ten units OK. Anything in-between can be guessed at close enough for kayaking needs.

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MikeB
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Post by MikeB » Wed Apr 04, 2007 4:50 pm

Fill the hole - easiest option, it's in line of sight without having to look down and it looks cool!

Mike

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Cornholio
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Post by Cornholio » Wed Apr 04, 2007 7:30 pm

I got a yellow Suunto bungee attached one for my Capella. I "filled" the space for the Silva witha solid foam "wedge" to bring it level as a platform to put it on, then permanently mounted it with creative use of the bungee cords and the deck recessed fittings. Think they're about £40-£44 over here. Had a new one mailed from the US for £26 all in. Good old blighty.
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Post by geoffm » Wed Apr 04, 2007 9:22 pm

I have a Silva 85 on my front hatch cover, terrifically easy to read for 51 yo eyes :-)

Geoff

tommfuller
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Post by tommfuller » Thu Apr 05, 2007 11:24 am

Thanks for the feeback folks!

I expect I'll end up getting the 70P, just because it fills the gap, and sounds like it should be adequate for keeping on a bearing. I guess it just seems awfully small and far away compared with what I've been used to when sailing! I'll go and have a look at one in the flesh and see what it looks like a couple of meters away....

Jim, I'm interested in the hijack!

Cheers,

Tom.

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Jim
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Post by Jim » Thu Apr 05, 2007 12:16 pm

Aiming for some open crossings over the next week or so, the hijack debate will kick off or not after that :-)

Jim

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JulesT
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Post by JulesT » Fri Apr 06, 2007 8:43 am

I use the suunto orca compas which straps across the decklines and can be nicely positioned at the forward end of your map on the deck. At this distance it works perfectly, its in the line of site and is very easily readable. Any compass placement around the front hatch area is bound to be difficult to read as its just too far away. My GPS is in a waterproof case that straps across the D rings on the spraydeck.

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Bruxy
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Post by Bruxy » Fri Apr 06, 2007 1:58 pm

Hi Tom,

I too use the Suunto Orca and have found it a fine compass.

Having fairly poor eyesight, a compass mounted too far towards the bows would be impossible for me to read - especially when salt spray is smeared across my glasses.

The Orca is easily mounted anywhere you have deck-lines, the base moulds to slight curves in the deck and it's card is well dampened.

I tend to mount mine as shown - far enough away to avoid parallax issues yet close enough to be easily read. It's also far enough away from anything ferrous in my front hatch to avoid deviation ... worth watching if you have your GPS on deck too.

Cheapest I've spotted on a cursory look round at just over 32 quid is here:- http://www.sailgb.com/shop/basketview.asp

Nice compass!

Cheers
Chris





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steve-m
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Post by steve-m » Fri Apr 06, 2007 8:39 pm

[quote="Bruxy"]Hi Tom,

I too use the Suunto Orca and have found it a fine compass.

Agreed, I also have a Suunto and the numbers stand out fine and clear.
My question about compasses is how accurate are they? or to be more precise how accurately are we reading them?

As a group when we have called out a bearing we do tend to find that not everyone immediately heads off in exactly the same direction! with a mixture of Suunto and Silva compasses we have wondered if there is a discrepancy between compasses? However, usually when we check all the compasses are within 5 deg of each other. Any difference beyond 5 deg seems to come from differences in line of sight and the arrangement of the compass on the deck.

Regards Steve
Steve-M Shropshire

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geyrfugl
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Post by geyrfugl » Wed Apr 11, 2007 10:23 pm

I have a Silva 85 compass which I bought from Knoydart Kayaking
Systems (although readily available and possibly cheaper from your
local boat chandlers if you are near the sea). It's clear and easy to
read, and hasn't suffered too much from being permanently mounted on
my foredeck (I can remove it by unscrewing four non-magnetic stainless
steel bolts, but very rarely bother). The one fault it had was that the
plastic bezel surrounding it was a bit easy to move and I lost it by
bonking it with the paddle during some rolling practice. It now has a
turned wooden replacement which matches the boat, but is a bit
clunky - I should really do a bit more work on it :-)

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active4seasons
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Post by active4seasons » Wed Apr 11, 2007 11:22 pm

Another vote for the Suunto mounted on the front hatch or even further forwards.
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Jim
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Post by Jim » Thu Apr 12, 2007 9:09 pm

Jim wrote:Aiming for some open crossings over the next week or so, the hijack debate will kick off or not after that :-)

Jim
I think for the moment life is too short to bother with this, it is going to have to be artfully fabricated and even then most people would probably see through my devils advocate viewpoint. I was hoping to play in "magnetic anomoly" or possibly "strong magnetic anomoly" to generate some misleading evidence, but we didn't get to either them or "breaks heavily" (a more important objective). Oh well, a chart so full of promise and weather so full of wind!

Steve M - I think the reason that everyone goes off in different directions is in fact several inter-related things that boil down to 2 cetegories:
> Each boat handles differently
> Each person uses their compass differently

Most of the time my bow swings at least +-5 degrees from my general heading, for some people it is more for some it is less. What this means is that as the boat drifts off heading we notice it at different times before starting to correct it. As some boats depending on how well balanced they are and if the skeg is in use, will turn faster than others, everyone will take a different length of time, and thus distance to get back onto the correct heading. Then comes differences in how people get onto the correct heading, do they overshoot aiming to make a slight detour the other side of the course to balance the one they just made, or do they try and return to it in one go? Another variable is how often each person looks at their compass. Yesterday we paddled about 10 miles on a course of 90 degrees with wind from about 225 degrees and tide going about 0 degrees (wind comes from, tide goes to, both should have been pushing us north, and in fact were). When I first left land I was heading about 110 degrees as expected, but I had a slight weathercock, and the sea was quartering slightly, depending on your ferry angle (waves from between 180 and 270). Basically I had a bit much on deck still, the hike boots are the main culprits although the tent was on top too, I used to take a bivi and haven't really sorted out a location for the tent yet. Anyway, my actual course involved being turned upwind all the time to I guess 120 degrees or more - there were people in front of me so I didn't really check the compass very much whilst fighting the boat round from upwind back onto course, I just knew it was wrong. Having fought the boat back I was to the south of the guys so overshot and surfed down the waves for a bit before the wind got the better of me and turned me back upwind (by which time I was North of the rest). At this point I will mention that for part of the trip I was gaining on the others doing this, but had to stop occasionaly to fidget with pogies or water. Anyway, the point is that I only ever looked at my compass when I surfing down the waves and relaxed, therefore it would have been easy for me to beleive that I had in fact paddled at 60 degrees the whole way accross - that's what the compass said each time I looked at it.

I did however know that everything was running north so had my GPS failed I would have concentrated more and kept up an average of 110 degrees. My main navigational tool these days (and yes I do check the compass regularly in case it breaks down) is my GPS. On an open crossing in poor vis. keeping it on the map screen with the course line showing all you really have to do is alter your ferry angle to keep the little walking man on the line. If like me you wear glasses and they are covered in so much spray that you can't see the little man, keeping the line in the middle of the display works just fine.

My compass is a Silva with relatively large numbers every 30 degrees (I think - I was using it yesterday!), big marks every 10 and little marks every 5, I find this is all I need to be able to see to keep tracking my heading and if necessary to steer it, although I have to admit my compass is not much forward of Bruxy's - I have a smaller cockpit and larger chart area and I think my hatch is further forward but I bet the compasses are within about 6" of each other.

Jim

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