Trim tabs on Trawlers

[jclays]

Good morning
I'm new to trawlers coming from faster gas boats and still looking for my 38 aft cabin. In the mean time I am asking questions just because I don't know. Do Trawlers utilize trim tabs? I understand the Californians to be hard chined and flatter as you get towards the stern. More of a semi-planing hull. Would they benefit at all from trim tabs?
Thanks
Jim

 

[kchace]

A trawler with enough power to plane would, but I doubt it would matter on any trawler that has power to only do 8-10K WOT.


Ken

 

[fgarriso]

Most true trawlers run at 7-8 knots. I don't think tabs would work at those speeds.

 

[Keysdisease]

A large enough trim tab will effect the trim on even a full displacement hull, but those hulls don't usually lend themselves to enough real transom to make them work.

On Semi-Displacement hulls like thee olde Mainship to the left, absolutely they work very well. They need to be on the large size to account for the slower speed, but they trim the vessel fore to aft and port to starboard and help the vessel get on plane and stay on plane at lower speeds

 

[bayview]

If you don’t have the power to plane they are useless

 

[Bacchus]

A large enough trim tab will effect the trim on even a full displacement hull, but those hulls don't usually lend themselves to enough real transom to make them work.

On Semi-Displacement hulls like thee olde Mainship to the left, absolutely they work very well. They need to be on the large size to account for the slower speed, but they trim the vessel fore to aft and port to starboard and help the vessel get on plane and stay on plane at lower speeds

If you don’t have the power to plane they are useless

Agree on both counts.
Mainship had Bennett install stops to limit the travel on some of their late model years. When replacing mine I eliminated the stop and get much better performance. One needs to be cautious in following seas conditions and I beloieve this is the reason MS had the stops added.

 

[Comodave]

We have them on our boat which will top out at 17 knots. However since we always cruise at about 8.5 knots we have never used them since the sea trial.

 

[Nomad Willy]

Trim tabs on trawlers is just self inflicted drag.
We just don’t go fast enough to benefit.
The OP said on “trawlers”.

 

[dhays]

I have large trim tabs on my North Pacific 43. At my normal cruise speed of around 7 knots, they don't make a difference. On the very rare occasions when I feel like I just have too much money and want to burn it up in fuel, they can help starting at around 8.5-9.0 knots.


The original owner wanted them so the builder installed them. I would have saved my money.

 

[DavidM]

I had trim tabs on two so called fast trawlers.

On my 2006 Mainship 34T they added a knot or so to top speed and dropped the bow a bit. The boat was barely on a plane such as it is and probably was still mushing through the water at 12 kts.

On my 2003 Mainship Pilot 34 they were much more effective, probably because the cruising speed was higher- 14-15 kts vs 12 for the 34T. It would drop the bow significantly and add several knots at cruising speed.


David

 

[Rebel112r]

I have not been able to discern any change in trim. I have tried them in flat calm at all speeds that I travel at. They are a good place to place tools and parts though, when you are in the yard.

 

[Mikala]

Not trying to bust anyone’s chops, but if it has trims tabs it’s not a trawler.

 

[hollywood8118]

Not trying to bust anyone’s chops, but if it has trims tabs it’s not a trawler.

Most of us here dont own a "trawler"..


HOLLYWOOD

 

[hollywood8118]

There was a thread here a few years ago.. do a search and this was discussed at length before.


My O.A. 40 does have them and it makes a bit of difference above 7.5 kts or so.
For the same throttle setting at 1600 ( my usual cruise rpm ) I gain about 2/10 of a kt.
The bow does drop a bit and I do have better forward visibility from the lower helm.
They are a pain in the ass to keep clean and marine growth really loves them.
If I didn't have them I wouldn't add them as they don't do enough to justify the cost of install.. but I'm not removing them because there paid for and they do a little good.

HOLLYWOOD

 

[Slowmo]

Most 'trawlers' actually have modified planning hulls (e.g. Grand Banks, OA, Marine Trader, North Pacific etc). But cruising at 8-10KN its hard to see that they'll have a big effect. I've beens surprised at how many trawlers are equipped with tabs even though their power would limit them to 10kn max. I would not go so far as to say that if a boat has tabs it isn't a trawler since there isn't a definition of hull type for a trawler.

We have tabs on our Tollycraft but almost never move them (keep them neutral) since we're crusing 8-9kn. They only time they helped was to counter a bit of heel in a heavy cross wind, but even then it was a marginal benefit and probably cost me fuel.

 

[fgarriso]

Recreational trawlers are pleasure boats which resemble fishing trawlers. They can also be called cruising trawlers or trawler yachts. Within the category, however, are many types and styles of vessels.
A fishing trawler for example, always has a displacement hull for load-carrying capacity. Recreational trawlers, on the other hand, are as likely to have a semi-displacement hull. However, with the rising cost of fuel and the lower fuel consumption (though also lower speed) offered by displacement hulls, they are gaining popularity among some buyers. These displacement models typically have a cruising speed of 7–9 knots (13–17 km/h) depending on the boat length. Their maximum speed is often no more than 10–12 knots (19–22 km/h), whereas semi-displacement hulls can attain 14–20 knots (26–37 km/h). Recreational trawlers need only a small engine; 80 hp (60 kW) can be adequate in a 42 ft (13 m) boat, which will use less than 25 hp (19 kW) to cruise.

 

[lipets]

All the swift trawlers have them

 

[Simi 60]

All the swift trawlers have them

Not a trawler

. Recreational trawlers, on the other hand, are as likely to have a semi-displacement hull.

Not a trawler

Most 'trawlers' actually have modified planning hulls (e.g. Grand Banks, OA, Marine Trader, North Pacific etc).

Not a trawler


You could call them a ski boat but just because you or someone calls it one does not make it so.

 

[lipets]

Not a trawler
You could call them a ski boat but just because you or someone calls it one does not make it so.

Just because you say so, doesn't make it so

 

[obthomas]

I have a marine trading Labelle 40, it is a 7 knot boat and has trim tabs. They work for me when my sister-in-law moves away from center to Starboard or Port.

 

[Simi 60]

Just because you say so, doesn't make it so

No, but your underwater hull shape does and vessel lineage says its not a trawler

The dictionary says its not a trawler

trawler
/ˈtrɔːlə/
noun
noun: trawler; plural noun: trawlers
a fishing boat used for trawling.

A descriptive article here with the actual mechanics/design principles behind it

https://www.soundingsonline.com/news/what-makes-a-trawler-a-trawler

 

[ranger58sb]

No, but your underwater hull shape does and vessel lineage says its not a trawler

The dictionary says its not a trawler

trawler
/ˈtrɔːlə/
noun
noun: trawler; plural noun: trawlers
a fishing boat used for trawling.​

A descriptive article here with the actual mechanics/design principles behind it

I suspect that means there's maybe only 1 or 2 members here -- on ahem, trawlerforum -- who have actual trawlers, by that definition.

Even though yours started that way (didn't it?) sounds like you're not using it for trawling, so you don't have one either.

OP's question could well have been; "Are trim tabs useful for some of these slow boats you all putter around in?" Most of the answers speak to that.

(I do NOT have a trawler.)

-Chris

 

[w8n4sun]

Our GA came with trim tabs, but they don't do anything. The faster we go, the bigger hole she punches at the bow and huge wake behind. Anything above 9kts and the gph reading go sky high - in fact we recently did a top speed run and the fuel consumption of 69gph almost made my heart flutter. At 7.5kts we're only burning 3.1gph total. At our normal 8.5kt speed we get 6.5gph. Anything above 9kts and the fuel curve rises sharply.

 

[lipets]

No, but your underwater hull shape does and vessel lineage says its not a trawler

The dictionary says its not a trawler



A descriptive article here with the actual mechanics/design principles behind it

https://www.soundingsonline.com/news/what-makes-a-trawler-a-trawler

What hypocrite you have a house boat down under


you better google a like better to support that weak argument.

 

[Jeff F]

I understand the Californians to be hard chined and flatter as you get towards the stern. More of a semi-planing hull. Would they benefit at all from trim tabs?

Yes, if you operate at semi-planing speeds. I have them on my hard chined semi displacement Mainship 34 and they make a big difference in the 8-12 knot range, improving speed, ride and forward visibility. I'm sure it's a similar case for the Californians.

 

[Simi 60]

What hypocrite you have a house boat down under


you better google a like better to support that weak argument.

You are sounding angry, I can't even make sense of your last line.
And FYI, our vessel is an actual ex trawler fitting the description in that linked article almost exactly.

. The little trawler in the drawing is F/V Cressy, a New Zealand design (http://www.starkbros.co.nz). With an LOA of 52 feet, 6 inches, beam of 16 feet, 8-3/4 inches, keel draft of 8 feet, 2 inches and fully loaded displacement of 101.91 tonnes (224,674 pounds), she makes 9 knots powered by a Cummins NTA-855-M 330-bhp diesel running a Twindisc transmission with a gear ratio of 3.92-to-1. The 330 horses turn a 43-inch-diameter four-bladed propeller with a pitch of 43 inches through a steerable nozzle providing a bollard pull of 4.7 tonnes (10,362 pounds).

This was her in a previous life.

 

[caltexflanc]

Just because you say so, doesn't make it so

And just because a manufacturer calls it a trawler doesn't make it so either. Or anything close. As the Bard wrote, though, "What's in a name?"

 

[Kingston Mariner]

There was a thread here a few years ago.. do a search and this was discussed at length before.


My O.A. 40 does have them and it makes a bit of difference above 7.5 kts or so.
For the same throttle setting at 1600 ( my usual cruise rpm ) I gain about 2/10 of a kt.
The bow does drop a bit and I do have better forward visibility from the lower helm.
They are a pain in the ass to keep clean and marine growth really loves them.
If I didn't have them I wouldn't add them as they don't do enough to justify the cost of install.. but I'm not removing them because there paid for and they do a little good.

HOLLYWOOD

Timely thread.


That's helpful information. The trim tabs on my O.A. 40 were removed by a previous owner sometime in the past and I've been considering their usefulness. I haven't had a situation where I thought to myself "I sure wish I had trim tabs". I think I'll go ahead and remove the remaining wiring and joystick control.

I also need new chain. If the bow on our boats tends to ride a tad high perhaps going all chain will help keep the bow down. I would have thought that with 200 gallons of water under the forward cabin bed, if anything the the boat would be bow heavy.

 

[stubones99]

All the swift trawlers have them

They have them because they go faster. The slower you go, the bigger trim tabs have to be effective. At 7kts, you would need half a sheet of plywood. If you're running 20kts, getting the bow down and lowering the plowing effect of the vessel will increase performance and let you see better over the bow.

As a kid, almost every kid "flew" their hand out of a moving car. At low speeds, the angle of your had would have no effect, but at road speeds, you can fly it up or down with the slightest rotation.

 

[Poach]

trim tabs

They are useful to "trim" the ride of the boat. Sometimes due tankage, passengers, grog in the locker and other weight distribution variables, I might want to be able to level the boat. Sometimes due to sea conditions, I might want the bow up, down or neutral. I have not noticed a significant difference in fuel burn with these adjustments. Finally, and I saved this for last, when I go fast, having the ability to trim can aid stability and handling.