Harken MKIII Furler line assistance

dlochner · Friday at 3:46 AM

7/16" llne is rather beefy line for a Furler, 5/16" is more typical.

Line diameters are nominal, that is to say they are not very accurate. Take a look at this video from now defunct Annapolis Performance Sailing on measuring line diameters. While APS is long gone, their excellent videos remain on YouTube. Watching them is time well spent.

Marmalade · Friday at 4:33 AM

The manual you linked is for a Unit 3... I don't know your boat, but based on the picture, doesn't look like a Unit 3!

Look at bottom chart in that P2Marine identification guide... I don't remember the exact recommendations, but Unit 0 is for <30ft boats, Unit 1 is 30-35ft range... really based on sail size, so just a guideline.

As @dlochner said, 5/16" or 8mm are the common line sizes, and the Harken Mark III Unit 1 says 5/16"

Unit 0 might be 9/32" or 7mm... you'd be best to verify.

sorry to say the 7/16 line you purchased will likely have to be repurposed!

Scott T-Bird · Friday at 6:28 AM

So it appears that the previous owner put a Unit 3 on the boat when he didn't really need it to be that beefy. I don't know why a smaller line size couldn't be used and perhaps that is why he has it on there. But, since you already bought 7/16, you may as well use it since that is what is recommended by Harkin. Put it on and use it. Who cares if it is stronger than it needs to be for the size of your boat?

The jamming may be a separate issue. No telling what it could be about. I don't think the line size makes a difference. I know that when I let the sail spin out uncontrolled when I'm pulling the sail out in a breeze that my line jambs. It is crucial to keep some tension on the line when you are pulling the sail out so that the line winds tightly. (It's just like the old days when my dad was teaching me how to keep my thumb on one of those old casting reels with the open face. I lost a huge northern pike when I was about 12 years old because I let the reel jamb on a cast.)

You need to be careful not to burn your hand if you are holding the line. I usually put a wrap on a cleat to keep it under control.

(If it's not really a Unit 3, you should verify which model you have)

jssailem · Friday at 7:32 AM

zinahewitt said:
I had a look at the line I removed ...... kept jamming.

Was the previous owner clueless and put the wrong size line in.

If you have an MKIII Furler what furling line do you use ?

I have a MkIV Harken furler. I have seen and used in a past experience the MkIII. It is older but a solid piece of harware. State of the are in it's time.

Your questions started #1 with the statement that the line kept jamming. Can you explain that? Does jammining gmean tha the line wrap is too tight and you are getting overwraps on the drum? This could happen not because of line size but due to age or dirty line. Over wraps can happen when line whips out or in on the drum as the sail is being deployed or retreved under pressure. Similar to how over wraps occur on a jib sheet winch. Slack line on the furler line is a third possible culprit. To address this issue I would give the ine a good wash. I would make sure the line wraps smoothly on the drum. I would check the fair leads to be sure they are guiding th eline at the proper angle to the drum to allow the line to wrap smoothly about the drum.

#2. Perhaps the PO bouught the wrong size or allowed the maintenance to become slack. Who knows?

#3. If you choose a larger size yu will get fewer wraps on the drum. This may be fine for the size of sail you have. The size listed in the manual is a guide. If you need to more wraps on the drum you need a smaller size line. The line size is adjustable to the needs of the boat owner.

dlochner · Friday at 8:13 AM

zinahewitt said:
Item 2.
I had a look at the line I removed from the sailboat which kept jamming.
It was roughly 8mm , which seems to be 5/16.

The most common cause of jamming on roller furling is halyard wrap. This is caused by another halyard getting caught in the furler or the angle of the halyard to the upper swivel is incorrect which allows the halyard to wrap around the foil.

Another cause is inadequate backstay tension, the headstay sags and and it is harder to turn the drum.

A loosely wrapped furling line or a poor lead from the drum to the first block will cause the furling line to get an over ride.

Ward H · Friday at 9:59 AM

If you go ahead and install the 7/16" check for excessive friction going through the fairleads to the cockpit. If the old line is 5/16" the fairleads might be sized for the 5/16". The 1/8" bigger line might not fit or drag.
I doubt I could fit 7/16" line through the Harken fairleads I bought and I don't remember their being a choice in size.

Edit: I just did a quick check. Harken's Stanchion Mount lead block kit shows max line size of 3/8". The ratchet blocks are 57mm. You'd need 75MM blocks for 7/16" line.

dlochner · Friday at 10:08 AM

Ward H said:
I doubt I could fit 7/16" line through the Harken fairleads I bought and I don't remember their being a choice in size.

@Ward H your memory is still good. The Harken fairleads are sized for 5/16" and even that can be tight.

Harken MKIII Furler line assistance

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