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Smart Trim Tabs

From www.imsupplies.co.uk Tel  01427 891144

Phill Williams reluctantly gets trims tabs fitted to his Warrior 165 but soon finds the benefits.

Volunteer

As the Warrior workshop is no more than 10 minutes from where I live, it has become something of a Saturday morning haunt for me when the weather is bad. Talking boats and accessories is not as good as using them, but preferable to being sat in watching trees waving about in the wind. On one recent visit, Phil Byron pulled out a set of stainless steel trim tabs he had been given to trial, In particular he wanted to put them on to a Warrior 165 with a big heavy lump of outboard stuck on the back and was looking for a regular fishing volunteer. “You have a 4-stroke Honda 75 on the back of yours haven’t you”. I didn’t even get the chance to answer before he came back with “You’ll do. Drop it in on Monday and I’ll have them fitted ready for weekend”.

What are they?

So what are trim tabs and what can they do that power trim and tilt can’t do. If you’d asked me on that prior to ‘volunteering’ I wouldn’t have been able to offer much of an answer. Having now researched the subject I can tell you that trim tabs are ablong stainless steel plates with hydraulic plungers known as actuators fitted to each side of a boats transom. What they can do for a boat depends to some extent an correctly matching the right size of tabs to a particular boat and engine; weight displacement within the boat, and hull shape. By all accounts they lend more to V-hulls than other designs. And what they can do for a boat that power trim and till on its own cannot do is allow the outboard prop to work in a more efficient economical manner than it does than being used to stabilise a running boat.

Transformation

When we put sea the following Saturday after the fitting, we knew absolutely nothing trim tabs which was good from the perspective of going in to the trial with a completely open mind. Within half an hour we had made an initial assessment which we were later to find matched almost to the letter manufactures claims made on the internet. The transformation was the equivalent to putting to sea in a brand new boat built and balanced up to our personal specification. It was that different.

Subconscious

Over time you tend to learn the characteristics of the loading, layout and performance features of your own boat and know instinctively what to expect under any given set of conditions. As such, you probably subconsciously adapt to it probably don’t even think about improvements to performance, economy and safety until something like trim tabs comes along to highlight the differences for you. Its hard to believe that a stainless steel plate fitted either side of the outboard could possibly make so much difference. But it does.

Table of trim tab requirements

Weight Distribution

Let’s start by looking at the makers claims. Most bots (they say) are designed to plane at a particular speed and weight distribution. Too much weight, particularly when distributed towards the back of the boat in the form of batteries, fuel and a big heavy engine causes the stern to dig in deep leading to in-efficiencies. Other aspects of unbalanced weight distribution such as me at 11 stone on one side, and Dave Devine at 6’ 4” and 18 stone on the other introduces further in-efficiencies as well as stability problems.

In a Stroke

Under power, un-even weight distribution causes the bow to rise leading to reduced visibility and hull slamming. The knock on effect of this is getting hammered to death in any sort of sea, poor fuel economy, reduced acceleration and top speed, and reduced safety due to instability. According to the manufacturing blurb, trim tabs correct all of this at a stroke in a way that power trim cannot, allowing the trim button to be used to adjust the angle of the prop to the point where the thrust is running parallel to the water flow bringing even greater fuel economies still.

Faster ride

In a nutshell, our Warrior 165 ran a good 4 mph faster than its previous recorded best. Acceleration was also noticeably improved, as was lateral stability and quality of ride. No more slamming or porpoising, and we were able to use the power trim at a much more efficient angle than previously. all of which has to relate to fuel economy., particularly when slamming or porpoising, as the hull was not experiencing intermittent bouts of drag caused by contact with waves. All of a sudden that seven stone weight discrepancy between Dave and I seemed to vanish from the equation. The only negative I can think of is having to take extra care to avoid bottom contact when launching from an open beach.

Automatic adjustment

The actuators on Nauticus Smart Tabs are nitrogen gas filled adjusting automatically after making the initial optional set up choices. These hold the plates down during acceleration, the degree of actual lift being controlled by the initial adjustment, the tabs start with a downward angle to maximise stem lift (minimising bow rise) allowing the boat to plane more quickly. It should also plane at around two thirds of the speed previously required which is a vast improvement, then water pressure acting on the plates as they dip down exceeds the actuator load rating, they are pushed up into a horizontal position to eliminate drag, though smaller subtle adjustments continue to take place to improve stability, while reducing popoising and sliding.

At a little over £2000 per pair fitted, they are not cheap. In theory that cost should be recovered in fuel economies over a period of time. But that aside, the difference they make in terms of top speed, acceleration and stability as a percentage of the total outlay for a decent outfit is more than worth the cost in its own right.