Rocking

I have a 1978 Thompson Trawler 36’. I have completely restored , but found that it is extremely rocky if caught in waves or wakes.....is this a common problem with these Trawlers, or is there any suggestions? Appreciate any help.

Welcome aboard. Rocking is a pretty subjective term. What is rocking to one may be normal to someone else. How much boating experience do you have? Have you been out on a similar boat so you could compare yours to another? If not maybe hitch a ride on another boat that is similar to yours and see how they compare. What you need to determine is whether it is actually dangerous or just uncomfortable. Goos luck with your new baby.

Common problem. Especially if you have shallow draft and high bridge. Don't take the waves beam to. Try a zigzag course. Angle into them so you're hitting them on the bow quarter, then change direction so you're taking them on the stern quarter.

I check NOAA marine forecast and if waves are 3-5 I might wait a day until it settles down.

Same with wakes. Head into them, shoot a flare at the offender, resume course. I normally let it roll with wakes but will let my wife know one is coming.

There are passive stabilizers you can have applied to your boat, they are popular here in my area, used mostly by fisherman in the Strait of Georgia. One of the forum members expressed interest, I helped him with contact info for the guy who installs them in my area. He can go to other areas to install them. In boating dollars they are almost reasonable.

In a Pacific Yachting article, the stabilizers were and install was roughly $5,000.

Sound advice on waves. We have a 1989 Camargue and draft is 3.5. We made the trip from Blaine, Washington crossing the Columbia bar and she did very well.
Our dogs would beg to differ with that.

Seakeeper is an internal gyro stabilizing system. It's supposed to stop 95% of the rolling. Probably about $20Gs for your boat.
https://seakeeper.com/

Thompson trawlers are hard chine boats....Most were made as commercial f/V's and have a reputation as a phenomenal seaboats for their size..... I can't imagine the yacht version is much different unless there has been lots of weight added up high, more than just the flybridge

Thanks, I know boating and how to take waves and wakes, never experienced such extreme rolling. This trawler has main deck, secondary deck and then up to fly bridge..I’m thinking this is just too top heavy...

Around 1980 a Thompson trawler berthed at my family's marina in Cortez, FL for a couple of weeks. She was a beautiful boat, great lines and a quiet engine.


That was the first time I was ever smitten with trawler envy.



Never seen another since then. Do you have any photos you can post? What's her beam? Any photos of her keel and running gear?


Cheers,
Mrs. Trombley

She’s a 14 ‘ beam, about a 3’ draft.....haven’t figured out how to add pictures, working on that.

There was a thread on Thompson yachts 2-3 years ago. Most of the Thompson’s were 44’ . Only a couple of 36’ models were made perhaps due to the issue you bring up. It might behoove you to do a search for that thread.

they were legendary on the southeast coast as commercial fishing boats. Rodney Thompson built a seaworthy vessel in both sizes. The 44 is much more common. The problem is in the added weight up high , I would suspect..

Commercial fishing boats have stability tests done so they can determine the amount of weight they can carry up on deck. I have no idea what it costs to have one done but if you are really concerned about the rocking then that might figure out if the flybridge is too heavy. Or get out a saw...

Have you tried speeding up? My old Mainship 34 is rocky at displacement speeds but gets much more solid and secure in waves at semi-displacemwnt speeds.

Tell us more about the boat!

Thank you all, It’s a nice boat. I’ll figure out.

Jeff F said:

Have you tried speeding up? My old Mainship 34 is rocky at displacement speeds but gets much more solid and secure in waves at semi-displacemwnt speeds.

Tell us more about the boat!

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Definitely give this a try. A lot of boats will ride better with more power applied. Getting into a worse part of the power / drag curve makes the boat's motion less affected by waves, as the bit of additional drag, etc. from hitting a wave is less significant relative to the drag from pushing through the water, so the loss of speed, etc. is less.

rslifkin said:

Definitely give this a try. A lot of boats will ride better with more power applied. Getting into a worse part of the power / drag curve makes the boat's motion less affected by waves, as the bit of additional drag, etc. from hitting a wave is less significant relative to the drag from pushing through the water, so the loss of speed, etc. is less.

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Op doesn't say what his power plant is but many Thompson trawlers (most) are single engine 8 kt boats.... 4-71 DD's were common in these boats

Good tip..........will try Thanks

Sailor of Fortune said:

Op doesn't say what his power plant is but many Thompson trawlers (most) are single engine 8 kt boats.... 4-71 DD's were common in these boats

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Even on a slow boat throttling up can help the ride. There's a lot more drag (and a lot more power applied) to hold the boat right at hull speed or just above (if it'll do it without the engine at WOT) than there is a knot below hull speed. Even though I've got a planing hull, if I'm running off-plane, the difference in ride between 6.5 kts and 8.5 kts (where I'm pushing just past hull speed and plowing a bit of water) is massive.

JohnRC said:

I have a 1978 Thompson Trawler 36’. I have completely restored , but found that it is extremely rocky if caught in waves or wakes.....is this a common problem with these Trawlers, or is there any suggestions? Appreciate any help.

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What about simply increasing ballast low down in the hull/bilge spaces ? What ballast do you have now?

rslifkin said:

Even on a slow boat throttling up can help the ride. There's a lot more drag (and a lot more power applied) to hold the boat right at hull speed or just above (if it'll do it without the engine at WOT) than there is a knot below hull speed. Even though I've got a planing hull, if I'm running off-plane, the difference in ride between 6.5 kts and 8.5 kts (where I'm pushing just past hull speed and plowing a bit of water) is massive.

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I would bet he has no more throttle to give it. Most 8 kt boats just go there and stay there. Are you familiar with Thompson hulls?

How about a number? 15º ? 20º ? 45º?.......