So you have just hauled your boat out of the water and you check the propellers, only to notice the anodes need to be replaced. You know that the propeller is a Varifold folding sailboat propeller, whether it is a shaft or sail drive type propeller, the diameter and how many blades it has. However there may not be much left of the Zinc anode to help with the identification! This post will help you determine which anode is it that you need!
So your anode, or what remains of it, looks like that in the photo below, a sliver of zinc around the anode holder. It is way past the time to change your anodes. Remember, if the anode is not in good working order, any stray current generated on the boat will turn the propeller into the anode and the erosion will be on much more expensive items. There is no hard and fast rule however to the wear rate. Some boat owners will use an anode a season, some considerably more. Factors that cause this include parking next to a steel or a wood pier, onboard electronics that remain plugged in while at the pier (TV, A/C unit), earth problems with the engine, and so on. I am working on a post to identify the common causes of cathodic erosion / protection to help owners protect their Varifold folding propellers, and their boats, better. So there are three basic types of zinc anodes for the Varifold range, which keeps things easy, these are:
- 2 blade Sail drive anode
- 3 & 4 blade Anode (propellers under 26”)
- 4 blade anode (propellers over 26”)
Sail Drive Anode (VF2SDA)
The first Zinc anode is shown below and this fits the 2 blade sail drive type Varifolds. The anode is unique in that it consists of two horse shoe shaped anodes that fit into a machined groove on the side of the propeller hub. The anode is held in place by a marine grade stainless steel countersunk bold on either side of the hub to keep it flush and in place. The hub on the sail drive is unique in so far as it is fitted with and internal torsional damper to protect the gearing of the sail drive should the propeller foul it’s blades, but this system helps to electrically isolate the propeller reducing the risk of cathodic corrosion.
3 & 4 Blade Anode (VF34AN)
The second and probably most popular Zinc anode for the Varifold is shown below; this is sometimes known as a “bullet Zinc” due to its shape and fits a wide range of folding Varifold Propellers. This anode fits the 3 blade Varifold range (VF-108) and covers the larger 3 blade sail drive units and also the 3 blade shaft version of the propeller. The anode is also fitted to the smaller 4 blade propellers (VF-120) which are less than 26″ in diameter. This Zinc anode is approximately 1.75″ in diameter and 1.75″ tall; it weighs just over 13 oz.
4 blade Anode (VF4AN)
The final Zinc anode common in the Varifold range is the 4 blade anode shown below with its fastening bolt. The anode is intended for Varifold folding propellers over 26″ in diameter, known as the VF-160 series of propellers. This anode is significantly larger than the 3 blade VF3AN anode and has a diameter of 2.64″ with a length of 2.64″ and weighs approximately 45oz. This Zinc anode also has an internal thread for attaching it to the propeller hub, but owing to its larger size, is fitted with an additional M8 x 60mm cap head bolt to secure it in place.
Varifold folding sailboat propellers are available in larger sizes still and the anodes for these are custom made. The largest Varifold Sailboat Propeller in service is in fact fitted to the 161 ft Orion of the Seas, a 1910 Camper Nichols classic. The propellers on this vessel are 46 inches in diameter 4 blade Varifolds, absorbing 210 HP per shaft, giving smooth quiet sailing!
Don’t forget you can order the above anodes for your boat anytime of the day. Simply visit http://kingpropulsion.market or give King Propulsion a call on Virginia (757) 962-9219 to chat about Varifold propellers!