Line Replacement for Outhaul in Isomat Booms H35 87 & 89 Models

[tedsouter]

Has anyone ever changed out the line that ultimately ties into a "magic box" I presume, and then is attached to a wire rope with a thimble eye for the outhaul system?

Slipmate and I both own an '87 and 89' Hunter Legend 35 here.

Mast and boom are both Isomat fabricated.

Both of us would like to replace the now twenty plus year old lines?

Thanks in advance for any posts/replies...

Teddy Souter/Neragin

 

[walmsleyc]

I've had my boom apart, and I think there is only a 2:1 system inside, and nothing quite so powerful as a magic box. If my recollection is correct, the wire rope is simply attached to a small block. The external control line enters under the gooseneck, goes aft to the block attached to the wire, and then forward to a becket riveted to the strb inside front of the boom.

My personal feeling is that it could be replaced with a single line (no blocks on the inside of the boom) that goes in at the clew, and exist at the bottom of the gooseneck. Any purchase system could be installed between the gooseneck and the deck where, if anything goes wrong, it could be easily replaced or serviced.

Chris

 

[Bill Roosa]

Dito that

That is the way my 37.5 Legend was also. A real pain to maintenance.

 

[Steve Dion]

Can you just attach a new line to the old ones and pull them through? We did this on our HV'36 and it worked fine.

 

[Alan]

I completely overhauled the outhaul on my 35.5. It is all internal and in spectra. I bumped it up to 6:1 which makes it very easy to adjust no matter how hard its blowing. I used a 3 part arrangement that cascades off a 2 to 1.

 

[Honeyman]

Alan, was that your outhaul only? I believe you've explained before about how you changed out the "car/s" inside the boom that handle the reefing lines. Were you able to get the old parts out and the new parts in without drilling out the rivits that hold the end-cap onto the boom? I still need to rework my reefing lines...any info on the parts you used would be helpful.

 

[Alan]

Yes I did a complete overhaul of the entire boom. I replaced the outhaul and both reef systems. I did all of it without removing any rivets. It takes a little planning to get the lines through. I did remove the boom from the gooseneck which allowed me to tilt the boom enough to slide the blocks and lines through with the help of gravity.
The 'floating' blocks that are part of the reefing system are responsible for a large part of the friction in the single line system which makes it very hard to use and adjust. Swapping out these double blocks for good quality ball bearing blocks makes all the difference. Now getting proper tension in the reefing line is a snap. The foot and luff can be fully tensioned to flatten the sail properly. Makes a huge difference to sailing performance in big wind. The last thing you need in heavy air is a loose outhaul and luff.

 

[Honeyman]

Any mfg/model #'s for the ball bearing blocks and what size spectra lines used would be more than helpful. I'm mainly concerned with the reefing lines. I'm assuming you used some sort of smaller diameter line to "fish" out the old blocks and feed in the new blocks and lines. Had to be a fair amount of line to work each end of the boom for both reef points. Any elaboration would help me envision what you had to do to complete this re-fit.

 

[tedsouter]

Thanks from original Poster...

Just a note of thanks to all whom have taken the time to respond to this query. I'm going to tackle this as soon as I'm finished replacing the line for the internal reefing this weekend...

I'm intrigued by Alan's retrofit, it appears to be very robust, and what I'm looking for an much needed upgrade.

Again, thank you all, I wish you all a great, safe and joyous sailing season this spring/summer/fall!!!

P.S. I've uploaded, (twice), the cutaway diagram of the 35.5/35 Boom, this may be of help to all of us in the future, (thanks to Crabcake Bob!)!!!

 

[Mike H.]

Alan, was that your outhaul only? I believe you've explained before about how you changed out the "car/s" inside the boom that handle the reefing lines. Were you able to get the old parts out and the new parts in without drilling out the rivits that hold the end-cap onto the boom? I still need to rework my reefing lines...any info on the parts you used would be helpful.

I did this project on our 94 V36 last year.

I took the end cap off the boom and pulled everything out from the end. When I replaced the end cap, I tapped the rivet holes and installed bolts in lieu of rivets. The rivets or bolts just hold the end cap from falling off when there is no tension on the outhaul or reefing lines. It seemed easier than removing the whole boom.

The shuttle blocks for the reefing system inside the boom are poorly made. I found oem replacements from a vendor in the north east. I think he wanted $ 250. each. New blocks were more money. I pulled them out of the boom and removed the reefing lines. They were completely frozen. Tried soaking them in vinegar, blaster, wd40, oil, nothning broke tehm loose. Called isomat and the tech said take them apart by driving out the axels with a pin punch. I did that and discovered the pulleys are just a hunk of plastic, no bearings, just a disc with a hole. The bodies of the shuttles were unfinished, the casting fins and rough texture of the aluminum stopped the pulley wheels from turning. They probably never worked even when new. So I faired the insides of the castings with fine files and reduced the thickness of the wheels by rubbing the sides of the wheels on a piece of 80 grit sand paper on a table. After everything was all smoothed up, I put them back together and tapped the axels back in with a hammer and spun loose and free. Perfect. Then I re rigged the reefing system and it works fine now.

Those shuttle cars carry a big load and replacements are very expensive and maybe too big. Maybe thats why the originals have no bearings.

Hope this helps.

 

[Alan]

Mike you are sure right about those crappy floating blocks. I sure hope your mods last for a while, but rather than go through all that work you could have substituted a Harken 353 Carbo Block. At $25 its almost not worth the extra work and you're sure to have a very low friction system.

 

[Mike H.]

Mike you are sure right about those crappy floating blocks. I sure hope your mods last for a while, but rather than go through all that work you could have substituted a Harken 353 Carbo Block. At $25 its almost not worth the extra work and you're sure to have a very low friction system.

I'll check into that. I was told these blocks have to handle thousands of pounds of tension, therefore big blocks, big price.

 

[Alan]

Mike, it's more on the order of hundreds of pounds. These little Carbo blocks are rated for 330 safe working load and a 1000 pound breaking load. They've held up just fine for me for at least 6 or 7 years now.

 

[tedsouter]

2nd Follow Up Post on Outhaul - Mystery Solved!

Another follow up from original poster here: Attached pix below is what I pulled out of my boom, note the unused block with wire rope on boom end with 7/16" line on the other. I can't help but wonder how this was rigged up originally, I'm the third owner of boat, I think!

While I just replaced with straight 5/16" line, I've now at least routed it back through open deck organizer and to a spare rope clutch that was available, my H35 is rigged for simple operation and single handling! I'm just trying to make it a little better while replacing all line this year...

Thanks again for all the posts!

 

[Alan]

Ted

That block and wire rope setup was part of the original outhaul. The other end of the wire rope was riveted to the bottom side of the boom near the front. My setup doesn't use any riveted parts. I simply hung the wire rope eye on the front axle of the boom sheaves.