Trawler Stability - 2nd Opinion Wanted

We completed a survey on a trawler we are looking at purchasing and our surveyor felt that the boat had a slow roll response during the sea trial and is thinking we should do a stability analysis. We have explored the stability analysis option, but we're running into many roadblocks. We felt comfortable with how the boat moved and we are thinking instead of doing the stability analysis, to have a captain who is very familiar with trawlers provide a 2nd opinion on the boats stability during another sea trial. We've realized that if the surveyor we used didn't have negative thoughts about this, then we'd be purchasing the boat right now. Does anyone happen to have any leads that could help us find this captain??? Hoping for the sea trial tomorrow (10/11) or Sunday (10/12) in Bellingham, WA.
Thanks!!!

What make you think some off the shelf captain has any better opinion than the surveyor?

A bunch of varied opinions may help, or a really highly rated captain or second surveyor...even better a naval architect ...but by tomorrow? Good luck.

A slow roll might be a couple of things...the worst is that the boat with a slow roll has a stability that isn't very good if there is any "hang time" when the boat is at the most heeled point. The boat.... even with a slow roll should reach it's maximum roll, but start back upright immediately.

What trawler?

My own view is that displacement trawlers roll a lot, but slowly and easily managed. Semidisplacement trawlers roll less at first but in heavier seas they sort of snap back and forth.

Beyond those two generalities, there are no bad trawlers or good trawlers in terms of rolling. Almost anll are semidisplacent hulls, btw.

David

Unless they were grossly modified by the previous owner(s)...then any stock trawler could be light years better or light years more dangerous.

A hanging roll is a well known telltale of stability in question.

What boat are you looking at?

What is a stability analysis? Why did the surveyor recommend one?

I'm with Psneeld (#4) - finding a "captain" to render an opinion is useless. I used to do buy-side boat purchase consulting and I have no idea what this means.

I realize many buyers approach forums like TF with caution about divulging the details but frankly without details on the boat, location, and intended use, answers are useless. Asking for a timeline of one or two days is insane. You're the buyer - in this market, buyers are harder to find than sellers. Don't be pushed around by a manufactured sense of urgency.

Good luck with whatever you decide.

Peter

So you liked the boat on the sea trail and the survey didn't bring up any hang points either?

Just the surveyor was concerned about "slow roll"?

Me thinks the surveyor wants to buy the boat -

Seriously, if the boat is a known "good item" and you liked the survey and the sea trial...

Yeah, what is the boat?

Jklotz said:

What boat are you looking at?

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Same for me - tell us what the boat is. Is it a known model, or a one-off?

Any further investigations should be done by a naval architect. That's their job. A couple of recent threads might be of interest

Thanks to all who relied. We learned today that our surveyor is writing it up such that it will require us to do a stability test (completed by anaval architect) anyway (per insurance), so we are moving on with that (we've worked out the kinks we had with this option) instead of using trawler knowledgeable captain for a 2nd opinion.
At this time we'd rather not say which boat it is. It is a one-off boat, not from a major, well-known manufacturer.
Thanks all.

First post says you’re comfortable with the roll, is this an opinion backed by experience?
Boats roll, it’s their nature!

Having pored my way through the Eliza 1 Coronial Inquest findings I posted (see post 9 above) I recognize the OP`s alert is reasonable. A skilled skipper could be helpful, a naval architect better but less readily available and ? cost. Seems from silence the boat make won`t be identified, but consider its age and engine hours. While usage detail would help, has it been around a while without sinking? Consider that with those observations in the Survey, what might an insurer reading it think. And if one declines, you need to tell other prospective insurers. So be wary, for several reasons.

Nick F said:

Same for me - tell us what the boat is. Is it a known model, or a one-off?

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The OP has answered - it is a one-off.

As such, there is no market history of this vessel's performance. It would also appear to be meaningless to say "what the boat is".

When deciding to buy a trawler was struck how different it is to compare stability in power compared to sail. First problem is getting people to talk or give data about objective measures of stability. Next problem is to be rigorous about what they mean when they say stability. Stability is a generic term. There’s multiple meanings to that word and multiple measures to define the specific characteristic under discussion.
In sail one can easily get an angle of vanishing stability and. Gz curve. The area under curve tells you something about speed to self right or if it will before further downflooding. You can look at how righting arm develops and likelihood if engine intakes or other piercings will be submerged at what angles and stay submerged for how long.
Then independent of stability as such there are multiple measures to assess comfort.
Here I totally agree with prior posters. All measures of the different types of stability are fairly simple math. As are measures of down flooding risks. Naval architects do this for a living. They may need to go to your boat to see modifications or placement of movables but generally can do this if given the particulars of your boat from their office.
Assuming this is a series production boat would first contact the builder. Given this boat is a one off would find out who the builder was and what analysis they did of the design.They well may have this data at hand and no further money need be spent. Only time to asses if modifications were made which might affect the data. If not engage a NA. For a one off in the absence of prior analysis they likely will need to come to the boat. Hopefully you can get information about the weight and placement of major components. They may be able to give some insight but complete analysis might be prohibitively expensive.

From OP in post #10....

"At this time we'd rather not say which boat it is. It is a one-off boat, not from a major, well-known manufacturer."

If the boat is a one-off built to a set of plans drawn up by an NA, then verifying the build is to the plans is what is most important. I would guess in drawn-up plans there would be some basic stability numbers or could be obtained if the NA or firm, etc is still around.

However if there are and changes to that original set of plans, a new set of stability numbers should be developed by a qualified professional that will satisfy not only the OP but if an insurance company gets interested.

How long it take to roll : portside/starboar/portside
Our long-cours was 2.5" , when we discuss with Dashew he don't want give the real number he said between 3 to 4".
When we sold our LC62' the surveyor said to us move at 10kts and turn one side quicker than possible ...our LC62 ' stay near horizontal ..but it could be dangerous to do that with boat with poor stability...
We saw one NH46' for sale ...when we saw all they put "upstair" we was scary about stability.

Take a captain and do a trial ...it will be better to check the stability with real number .
Charge one side check the angle do basic calculation .
You got a real number with that and the boat caratéristics you can have the kg/m you have at each angle until ...0, and at witch angle this zero will happen (in theorize because static).
When we doing that for our LC62' the "0" was at 93° WITHOUT taking in count the volume of our roof, it means in théorie "self-righting"

"...it will require us to do a stability test (completed by anaval architect) anyway (per insurance), so we are moving on with that (we've worked out the kinks we had with this option) instead of using trawler knowledgeable captain for a 2nd opinion."

100% the best way-forward, @Aurelia-Lang.

There would have to be significant weights loaded up on the boat deck / flybridge to affect stability to the point where a total stranger (you), who is unfamiliar with the boat, notices it and is greatly concerned. So unless there is a very large Boston Whaler up there plus a top load freezer full of salmon plus a dozen scuba tanks, then there is a very real possibility that the boat was not built to the plans or that the original plans were deficient in their calculations. The solution may be as straight-forward as adding a ton of lead down low, but that same nautical architect will be the one to determine that.

Big question is who is going to pay for any remediation efforts? They could get expensive. Keep us updated as this is a very interesting thread.

Yeah, one-off boat with a surveyor alarmed at the hang? I would have walked away because the boat is probably going to be uncomfortable no matter what the naval arch has to say,

Out of curiosity, measure the roll period at the dock. I believe it was Ted Brewer who said that a comfortable RP is 1 second per meter of beam.

So for example if your trawler has a beam of 16ft then a roll of about 5 seconds should be comfortable.

It would be great if you could quantify what "a slow roll response" actually means. I assume that the naval architect will be taking exact measurement of roll, acceleration, "hang", etc.

This was a one off post.
If not the boat, a more detailed explanation from surveyor would be nice to read. If valid, I would walk from this one.

I once hand a few moments of hang at the ends of the roll in my Grand Banks 42. I discovered 15 adults on my flying bridge watching the whales go by. That weight distribution got quickly resolved after a bit of shouting

Look at the NH actually for sale and compare them...
One have :
2 mast
2 pool t for paravane
1 flying bridge
Tender
Several grp big box to store stuff
Sitting banquette in grp
Bikini with lot of big stainless steel pôle
Lader and nest on the main mast
++++
If we bought this boat we will remove and cut undred of kg from the top

Mako said:

Big question is who is going to pay for any remediation efforts? They could get expensive.

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I think that's premature. A NA may be able to offer professional assurance that the boat is suitable for intended use as is. That's the ideal outcome, and is not unlikely.

I'm wondering whether this might be increasingly common as a bit of a CYA for surveyors. I'm in Chicago and there's a Silverton ~35 here that capsized this summer with loss of life. It doesn't take many deaths for stability concerns to become more widespread.

Why buy a "one off" when there are so many well designed trawlers out there? Besides the squirrely handling noted by the surveyor, resale will be abysmal.

mmullins said:

Why buy a "one off" when there are so many well designed trawlers out there? Besides the squirrely handling noted by the surveyor, resale will be abysmal.

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There are some wonderful custom one-offs...most production boats are designed and outfitted by marketing more than anyone.

What true cruising boat doesn't get highly modified after leaving the factory?

Wouldn't it be nice if a lot of those mods were designed in?

If I am not mistaken, it wasn't about handling but an unusual slow roll.

Slow rolls are not necessarily a stability problem, it's when you hang at each end of a roll that can suggest an issue. He needs to find out which is what for that boat.