Monday, September 21, 2009

Hood Seafurl 800 Bearing Replacement

rev. 7-1-2016

On a pleasant windless day at a dock 150 miles from home, I decided to partly lower our furling genoa so that I could put a few stitches and necessary patches on the sacrificial leech cover. A simple morning task to pass the time in a sailorly way. We were 10 days into a 2 1/2 week cruise around the Delmarva. I released the halyard tension, lowered the sail a few inches, and watched 48 ball bearings merrily dribble onto the trampoline, filter through the netting, and plop into the harbor.

The furler had been prone to catching for the past few days. It would roll fairly easily for a bit, then seize, and after a good tug, roll easily again. The bearings in this furler are half-and-half stainless and Torlon, and it seems the Torlon bearings had worn down to where the stainless bearings would ride up over them. Eventually, the wedging force pushed the lower circlip out of its groove and the lower race fell apart, unnoticed. My genoa is a little to long on the luff but still, it sets very well with no halyard tention; in fact, some wieght rests on the tack, just a little, and this held the upper race in position. When I went to re-hoist the sail the the foil was lifted by normal friction in the groove, the top half of the furler was lifted, and everything fell apart.

Although I could no longer furl the sail, I could still use the luff extrusion as a foil, so we lowered the large geona and planned on using the much smaller self-tacking jib for the 3-day trip home. The weather forecast called for strong winds on the nose the first day, followed by spinnaker reaching conditions for the next two days. That is how it worked out, so the loss of the furler was no great handicap.

Back at home, after considerable stress over the great cost of replacement unit, I set about disassembling the furler drive. It is a simple matter: bring the jib and spinnaker halyards forward and tension with winch; place a pad under the boom and release the topping lift - this relieves some tension from the forestay; remove the plastic set screw between the luff extrusion and the drive tube, remove the split aluminum castings, and while supporting the luff extrusion, gently lower until it rests on the turnbuckle - the luff extrusion will slide right through the drive unit; lift both the luff extrusion and the drive unit and place a vice-grip on the flats of the lower end of the forestay wire - this will support these parts and keep the forestay from turning when the turnbuckle is loosened; remove the cotter pins, and loosen and remove the turnbuckle - it was not necessary to loosen the shroud turnbuckles; remove the vise-grips and slide the furler drive off the forestay, while supporting the luff extrusion; replace the vise grips on the flats to hold the luff extrusion in place.

Replacing the bearings is quite simple. Each race (4 races) contains 48 x 9/64-inch 440C stainless balls, McMaster-Carr part number 9642K31. Parts are also available at Pompanette Co.. They are most easily installed by assembling the races first, and then inserting them from the bottom up, flipping the assembly over as needed. I used waterproof grease, but if you are using plastic balls and wish to assemble the mechanism without grease you will still need something sticky to hold the balls in place; tooth paste works and will rinse out. I have used it on other projects with Torlon balls. Be certain to tap the circlips securely into their grooves. Be careful to position the four
set screws into the matching holes in the drive tube. In my case I was not able to separate the stainless steel basket from the bearing tube and thus was not able to reinstall the furler line in the normal manner. However, a clove hitch around the spool with the stopper knot on a dead-end has proven secure. The heads of the set screws provide extra grip.

In my case, since I elected to get rid of the failure-prone mix of Torlon and stainless, I am using grease. To reduce the intrusion of salt spray I fitted a large (~3"x 1/8-inch thick, fitting just inside the tack fitting) polyethylene washer to the top of the stack, just above the top circlip. That is really the only place water can enter. I drilled a small drain in the stainless basket. We will see.

Notice that I also added a plastic ring above the furler as a drip ring, deflecting rain that drips down the forestay. Does it help? Not sure, but they are still smooth after 4 years. In a few more years I will open it up and re-grease, but for the moment, it feels and sounds (no squeaks or vibration--just smooth) like there is still grease in there.

What I am actually doing in this photo (11/2015) is spraying water NikWax repellent treatment on the furler line. I sail all winter and this prevents the line from freezing, which can be a big problem.

Piece of cake. I imagine I will be doing this every 5 years or so, under considerably less mental stress.


7-1-2016 update. Still smooth as glass.


  1. Drew,
    I am trying to rebuild my Hood 800 furler. My unit had the 9/64 balls that were badly worn in both the drive and the Halyard swivel. Pompanette as well as my manual showed they are now using 1/4" balls alternating between Delrin and Stainless. I live in Cleveland so McMaster Carr was a short drive. My problem is that with the 1/4 balls the grooves on the swivel tube no longer are in the right place. I suspect that thinner Thrust washers might correct this, but cannot find the recommended thickness when making this upgrade. The Thrust washers are .25" thick. After reading your blog I am wondering if I should go back to the original size. Any suggestions? Gary - Hunter 33.5

  2. First, I bet they changed some other dimensions when they changed to 1/4" balls. I suspect they went to every-other to avoid the need for stainless.

    As posted, I used 9/64" SS balls 4 years ago and it is still smooth as glass. I packed it full with a VERY washout resistant grease (Green Grease by Omni Lubricants, available through Advance Autoparts and NAPA) and added a plastic disk at the top to reduce water flow (see above). So that is all I know.

    Spoiler alert. I am into the 3rd month of a grease wash-out study for Practical Sailor Magazine, testing everything from the most expensive winch grease to some very common products. And the first place product is Green Grease, even better than Lanicote and winch grease. So I'm pretty sure Green Grease is the right call for practically everything marine.