Ask SAIL: Prop Zinc Deterioration - Sail Magazine

Ask SAIL: Prop Zinc Deterioration

Author:
Publish date:
Social count:
0
 Don’t be alarmed if the zincs are shrinking on your Flexofold prop

Don’t be alarmed if the zincs are shrinking on your Flexofold prop

PROP ZINC DETERIORATION

Q: My 2014 Dehler 38 has a Volvo saildrive 130S-F and a two-blade Flexofold prop. After six months in the Annapolis area, the two “small” zincs on the prop showed dramatic deterioration. In contrast, all other zincs (including the ring zinc on the saildrive) had minimal deterioration. Prior to launching the boat for the new season I did replace the two small zincs. This year I plan to keep the boat in the water for about eight months. Given the longer amount of time in the water (but also considering the fact that the saildrive zinc is virtually intact) do you think I need to replace the small zincs mid-season? If they were to completely deteriorate by season’s end, what is the worst that could happen?

Akis Goutzoulis, Annapolis, MD

NIGEL CALDER REPLIES

Calder-head

Volvo-Penta requires all metal propellers to be electrically isolated from their saildrive propeller shafts, which is almost certainly the case with your installation. If this isolation is maintained (you can check with an ohmmeter from the propeller to the saildrive leg; you should get a very high resistance) then the anodes on the propeller are only protecting the propeller, and the anode on the saildrive is protecting the saildrive. The propeller is a bronze alloy, which will inevitably eat up its anodes rapidly and probably does not need protecting in the first place. (Although Flexofold still supplies its propellers standard with anodes, it also supplies them without.) So I do not believe you need to replace the propeller anodes in mid-season, and in fact I don’t think you need them at all! That having been said, according to Flexofold you can actually replace them with the boat still in the water, as the mounting screws supplied with the zincs are pre-applied with a special Loctite compound. The critical anode from your perspective is the saildrive anode, which should always be replaced once it is half consumed. (Its effectiveness is directly related to the remaining surface area.)

Do you have a question for our experts? Submit it to sailmail@sailmagazine.com

Related

180615-01 Lead

A Dramatic Comeback in the Volvo

After winning three of the last four legs in the Volvo Ocean Race (and coming in second in the fourth), Dutch-flagged Brunel is now tied for first overall with Spanish-flagged Mapfre and Chinese-flagged Dongfeng following the completion of Leg 10 from Cardiff, Wales, to ...read more

MFS-5-2018-Propan-SP02

Tohatsu LPG-powered 5hp Propane Motor

Gassing it UpTired of ethanol-induced fuel issues? Say goodbye to gasoline. Japanese outboard maker Tohatsu has introduced an LPG-powered 5hp kicker that hooks up to a propane tank for hours of stress-free running. Available in short-, long- or ultra-long-shaft versions, the ...read more

TOTW_PromoSite

SAIL's Tip of the Week

Presented by Vetus-Maxwell.Got a tip? Send it to sailmail@sailmagazine.comThink Deeply When chartering, I am always maddened to be told that the echo sounder is calibrated “to depth under the keel, plus a bit for safety.” Such operators seem to imagine that the instrument’s sole ...read more

180612-01 Landing lead

Painful Sailing in Volvo Leg 10

It’s looking to be a case of feast or famine for the 2017-18 Volvo Ocean fleet as it continues the epic struggle that has been Leg 10, with it having been all famine thus far. Painful is the only word to describe the light-air start in Cardiff, Wales, on June 10, as the 11-boat ...read more

01-13_07_180304_JRE_03695_4605

Tips From the Boatyard

Within the Volvo Ocean Race Boatyard sits a communal sail loft which provides service and repairs for all seven teams sailing in the 2017-18 edition of the race. The sail loft employs only five sailmakers who look after 56 sails in each stopover. If you’re thinking, “wow, these ...read more

sailCarwBasicsJuly18

Sail Care for Cruisers

Taking care of your canvas doesn’t just save you money, it’s central to good seamanship  Knowing how to take care of your sails and how to repair them while at sea is an important part of overall seamanship. The last thing any sailor needs is to get caught on a lee shore with ...read more

Ship-container-2048

The Danger of a Collision Offshore

This almost happened to me once. I was sailing singlehanded between Bermuda and St. Martin one fall, and one night happened to be on deck looking around at just the right time. The moon was out, the sky was clear and visibility was good. Still, when I thought I saw a large ...read more

New-MHS-Promo

Multihulls on the Horizon

Fountaine Pajot New 42The French cat powerhouse has been on a roll these last few years, cranking out new models that not only replace their older line but take a step forward in design and user-friendliness. The New 42’s “real” name had not been revealed as we went to press, but ...read more