Article from Propeller Magazine

From Propeller Magazine – June/July 2004

A New Zealand company has developed a simple, easy to fit propeller guard that may just be the best protection against injury and accidents in the water from outboard propellers that you’ll find.

There are a number of prop guards on the market and while they can affect the boat’s handling and performance they all do the same basic job, protection of the propeller from hard objects and soft flesh! It’s the latter that has caused a number of fatal accidents in New Zealand in recent years and it was because of this that Safe Marine Ltd designed and developed the Prop Guard.

The Prop Guard is a simple aluminium ring that clamps onto the outboard cavitation plate and requires nothing more than a few minutes and an Allen key to fit it in place. Unlike the Hamilton made stainless steel Pro Pell as used by Thundercats and the variety of plastic guards from the USA, that have bars that ‘encase’ the whole front of the lower unit, the Prop Guard has two vertical protection bars, one either side of the lower unit that are hydrodynamically shaped to let the water flow over the surface with minimal resistance. The outer ring is also shaped much like an aeroplane wing with a thicker leading edge that tapers to the back of the ring. The whole ring weighs less than 1.5 kg.

Prop Guards come in a variety of sizes to suit most outboards from 2hp to 30hp. We took a #3 size Prop Guard and fitted it to a Yamaha 15hp on an Aquapro 1101 to see what the performance and handling differences would be. Without the Prop Guard fitted and running a standard 12” three blade alloy prop the boat recorded a top speed of 22.8 mph on the Lowrance GPS. For the speed runs we had one person aboard, no extra gear and a full 25-litre tote tank. Water conditions were mirror smooth, although as we did our testing the day after a week of gales, there was a lot of seaweed about on the surface.
With no prop guard the Aquapro leapt onto the plane with ease and reached the top speed in seconds. It was nimble to drive, responsive and at full throttle I was conscious about having the safety lanyard around my wrist, as I have been thrown out of a boat like this before.

So what was the difference with the Prop Guard in place? Firstly, I was impressed by the very little, if any affect it had on the boat’s handling. I found myself tossing the Aquapro around just as I had without the Prop Guard. Acceleration was also excellent, although marginally slower, but hardly worth considering. However, the drop off came at the top end with the maximum speed down to 20.4 mph at best.
It also didn’t like the loose seaweed which bound up on the leading edge of the guard and we lost traction! In reverse it simply wound itself around the prop and inside the ring, cutting off 80% of our thrust. I had to stop the engine each time and remove the weed before continuing.

There’s no doubt the Prop Guard does what it is designed to do and that’s provide underwater protection for both the prop and swimmers and divers. If you are looking for that protection and don’t mind a little drop off in top end speed, then we would certainly recommend the Prop Guard. It works and works well and for $199 it’s cheap insurance.

Manufactured from marine grade aluminium it is quick and easy to fit and only requires an Allen key to tighten the grub screws. While the instructions indicate that you should take the propeller off when fitting the Prop Guard I found it just as simple to put in on from the front and slide the clamps in place over the cavitation plate. This way you can line it up better and don’t have to move it when the prop goes on and you find it’s clamped in the wrong place. In some of the larger outboards however you will need to remove the propeller to fit the guard.

Make sure you tighten the grub screws up again after the first time you use it and it would also be prudent to check them a few times during the season. If you ever sell your outboard, then you can simply transfer it to the new engine.

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Website: www.propellermagazine.co.nz