The outhaul on my MC-Scow gets a lot of use and has caused its share of headaches, including needing three repairs, and also probably contributing to breakage of three tack slugs. My repair shop, S&R Marine in Pewaukee, WI claims to do plenty of repairs on outhauls, so I may not be an outlier. After talking to S&R Marine and John Porter, a frequent SailZing contributor, I’ve collected some tips to prevent outhaul failures.
MC-Scow Outhaul Design
The MC-Scow outhaul is a 2:1 purchase, with Harken components. The components are shown on the Harken website, although on the MC, the forward cable runs into the deck, instead of to a cleat. MCs also have an internal bungee in the backbone that is designed keep a small amount of tension on the system when you release the control lines. The layout in the boom is shown below.
Prevent Outhaul Failures
Here’s a collection of outhaul-related issues, either self-induced or due to normal wear, along with some tips to prevent them.
- Frayed cable. When you start seeing or feeling sharp wire ends on your outhaul, it’s time to replace the cable. Outhauls take a lot of tension, and fraying cable is a sure sign of upcoming failure. Time for a “boomectomy.” It’s hard to point when your outhaul breaks during a race!
- Worn through-wall pulleys. With all the load on the outhaul, the pulleys that feed the cable through the boom can wear and start to wobble. In one of my cases, this wobble allowed the cable to jump the pulley and get jammed in the space between the pulley and the boom wall. If you suspect wear, check the pulleys for wobble and free rotation.
- Twisted cable. The internal cable can get twisted inside the boom. If twist is introduced in either of the cables, coupled with on-and-off tension, they can cause the internal pulley to twist. Often, this does not happen right away, but becomes more probable as the pulley wears unevenly. Then, one day, you release tension quickly and the cable twists itself around the pulley. To help prevent this, try to prevent twisting the outhaul cables. Also, keep some tension on the outhaul when transporting it, using tape or by tying it off.
- Shackle accidents. If you sideswipe another boat with your boom (shame on you!) your outhaul shackle can hang up on the other boat’s sidestay and bend or break. This is slow, and possibly race-ending. I’ve seen people change the wire cable for some spectra line to prevent this, but not sue this is legal or the best solution. Any comments? Maybe develop a small rubber sleeve for the shackle?
Prevent Tack Slug Failures – Ease the Outhaul Before the Windward Mark
The tack slug is a plastic and steel u-fitting that anchors the tack of the sail to the mast with a shackle in between. What does this have to do with the outhaul, you ask? Well, I have broken at least three tack slugs in my sailing career, and it wasn’t until John Porter pointed out that you should ease your outhaul before rounding the windward mark that I started asking questions. Turns out, if you have a tight outhaul and then turn downwind, you’re putting a lot of side load on the tack slug, since the sail is pulling on the slug perpendicular to the normal loading. John says he has never broken a tack slug using this tip.
That’s all the outhaul tips I have. Share yours using the comments section below.
Continuous Control Lines: Quicker Trim Adjustment for Single-Handers
MC-Scow Tuning Guide and Speed Tips – UK PS1 Sail (emphasizes the need to adjust the outhaul)