How and Why to get your Prop Realigned - Sail Magazine

How and Why to get your Prop Realigned

The original purchase survey for my Allied Seabreeze sloop Keewaydin included a note about the fixed three-bladed bronze propeller: “some cupping noticed on all blades.” One of the surveyor’s post-purchase recommendations was to have the prop reconditioned.
Author:
Updated:
Original:

The original purchase survey for my Allied Seabreeze sloop Keewaydin included a note about the fixed three-bladed bronze propeller: “some cupping noticed on all blades.” One of the surveyor’s post-purchase recommendations was to have the prop reconditioned. That was a number of years ago, but I had studiously ignored the prop until last spring, when I finally decided to have it looked at.

I had heard about the benefits of computerized prop scans, so I sought out a local shop that uses this technology. Prop Scan, an Australian company, is a pioneer in the field and licenses its technology to approved shops worldwide. One of these is AccuTech Marine Propellers in Dover, New Hampshire. AccuTech’s president, Larry Kindberg, said they could do the work before I launched in late May and quoted me what I thought was a fair price.

But first I had to remove the prop, last taken off the boat at least 15 years ago. I borrowed a rugged prop puller made by Walter Machine and went to work. The aperture for the prop made for a tight fit, but eventually I got the puller set up correctly and began to tighten the nuts. Just as I was wondering if the project was doomed to failure, I heard a crack and the prop released from the shaft neat as could be. It was a challenge finding just the right arrangement of blade and rudder angles to open the aperture enough to allow the prop to slip off, but eventually, I had a three-blade prop resting in my hands.

Once in the shop, the AccuTech team put my prop on its Prop Scan machine and made careful measurements across each blade. Larry’s comment, “this prop is a complete mess,” was enough to convince me that I had made the right decision. None of the blades showed a matching, consistent pitch, they all had some cupping on the edges, and the prop itself was horribly out of balance. These factors all contributed to poor performance, including vibration, below-spec engine performance, and lower boat speed and handling characteristics.

After several days (spring is a busy time for any prop shop, and AccuTech is no different), I retrieved a beautiful, shiny like-new propeller. The boat’s name had even been engraved on one of the blades. AccuTech had gone through several steps with my prop—measuring, “adjusting” the blades until they matched each other (this involved a lot of noisy hammering), and then measuring again until its shape was perfect.

Installing the prop was pretty straightforward—no grease, just a couple of measurements to ensure proper location on the shaft and then a good tightening of the prop nuts.

The results? Less vibration, a noticeable reduction in the boat’s tendency to pull to the left under power, higher engine RPMs, and an overall improvement of at least a half a knot at cruising speed. Although I wasn’t initially sure propeller reconditioning was worth the trouble on a cruising sailboat, I am now convinced of its value. A quality shop like AccuTech services all makes and types of props, for all types of commercial and recreational craft, including feathering props. If you’re not sure your prop is true, it’s well worth looking into having it reconditioned.

Related

Photo-by-Adobe-Stockpics721-2048x

Webinar: Navigating Post-Dorian Abaco

On Thursday, October 22 at 6 pm ET, Navigare Yachting presents a webinar on what to expect from Abaco post-Dorian. The event will feature the authors of The Cruising Guide to Abaco, Steve Dodge and his sons Jon and Jeff.Hurricane Dorian hit Abaco in early September of 2019 and ...read more

LunaRossaBoat2

Luna Rossa Prada Pirelli Christens “Boat 2”

Hot on the heels of the UK’s Britannia and the United States’ Patriot, Italy’s new AC75 Luna Rossa, formerly known as Boat 2, was christened in Auckland, New Zealand, this morning. As the moniker suggests, it was Team Luna Rossa Prada Pirelli’s second design. In his christening ...read more

m7803_DSCF6698-1

Challengers Christen Britannia and Patriot

October 16 proved an exciting day for America’s Cup fans with the christening of both the UK’s Britannia and America’s Patriot. Britannia will be helmed by four-time Olympic gold medalist and America’s Cup winner Sir Ben Ainslie. Olympic Gold medalist Giles Scott will serve as ...read more

HookPromo

Defender Product Spotlight: Lowrance Hook Reveal

Defender product expert Alex Lyons explains the benefits of HOOK Reveal’s new FishReveal technology: “DownScan sonar uses high frequencies to provide a picture-like image of the sea floor. The traditional sonar’s lower frequencies are best suited for locating fish in the water ...read more

701820_promo

Defender Product Spotlight: Lumitec Poco Lighting Control

Several key features of the Lumitec Poco Lighting Control system stand out right away. First, it is a 2-wire system, so the average wiring-savvy boater can install or retrofit the controls without an engineering degree. Second, it works with any Power Line Instruction (PLI) ...read more

Isotherm

Defender Product Spotlight: Isotherm Refrigeration Component System

Retrofitting a refrigeration cooling system has never been easier thanks to Isotherm’s quick mount bracket. And installation is more than half the fun of boat projects, right? These refrigeration component systems also have one of the smallest footprints on the market, and the ...read more

WaveBreaker

Defender Product Spotlight: Superior Wave Breaker Life Raft

Designed for a hardcore offshore application, Superior Life-Saving’s Wave Breaker life rafts are heavy duty, easy to board, insulated and feature many benefits, including an industry-leading 4-square-feet of space per person aboard. The Wave Breaker line of life rafts is ...read more

003536D2

Defender Product Spotlight: Lewmar Heavy Duty Inflatable Yacht Fenders

After using the Lewmar Heavy Duty Inflatable Yacht Fender, you’ll never want to hoist another fender aboard your cruiser or sportfish. Made from 30% heavier material than the next best brand, it features 15% more tensile strength to provide protection for your hull when docking ...read more