Rolly custom steel motorboat

Do you know where she was built and who the NA was/is...?

 

Naval architects in the USA are considered engineers. They would only be in the register each state has if they also got a PE license.

 

If anyone is curious about the other discussion I have on a different forum, please visit this thread:

Steadying sail design/rigging? https://www.trawlerforum.com/threads/steadying-sail-design-rigging.71864/page-3#post-1249009

 

Not on trawler forum so I'll answer here, was distracted when this came up and didn't have time to fully answer.

You have a sailboat esque relatively narrow soft chine boat with a rather tall superstructure. It's near the perfect combination for a lively roll.

About 20 years ago the guys in my area were pulling similar type boats from the relatively protected waters of southeast to western alaska. The boats were a lot more efficient for the lower volume hook and line fisheries that were gaining traction at the time. All were faced with the same rolling issue. Saw paravanes fitted, keel plates, rolling chocks, even bigger rolling chocks, second rolling chocks, bulbs, bulbs with chocks, anti roll tanks on the roof.... even a few with all of the above. Eventually one of the more successful guys pulled the little gen, swapped in a biggun and spent the eyewatering amount for a suitable gyro.

Non but the gyro were silver bullets, just small incremental improvements and a trade off of downsides. We have a fairly famous hull form here known for its speed, packing and roll... can think of several with all manner anti roll counter measures. Non make it a hard chine beamier boat.

Keep in mind almost all the ideas will be small percentage changes, aside from six figures for a gyro retrofit it's all things that help but won't fundamentally make it a different boat. It's a concept worth keeping in the back of your mind when pricing out ideas.

Running joke in the boatyard was the efficacy of each measure was directly related to the price the owner paid... or at least in their mind.

 

If the stern air tank was removed, and additional weight incrementally added as Ad Hoc suggested earlier; would it help handling the seas?

 

Honestly it's hard to tell, that stern add on was kinda in the worst part of the boat for a smooth exit flow. Would hope whoever the na was that designed it had a solid reason to add a stern floatation like that.

Guessing it's a few thousand pounds of buoyancy, although hard to judge with perspective from pictures on a phone. Guessing they had a need for it from other topside alterations.

My broader point in the previous post was to highlight all the suggestions will merely improve on some small level the comfort of the ride. Some have downsides that offset the benefit.

Friend bought a shallow soft or slow taper chine boat, it rolled bad and he hauled and started glassing on the biggest chocks I've ever seen. Lots of feedback couldn't convince him otherwise that it might have unintended consequences. At any rate, in he went a week or so later with the biggest darn chocks you ever did see. Never for get him pulling out of the travel lift stall..... like a train on a track was the best observation. Probably 20 minutes later he was back in the slings and on the hard. Hull was still wet when he had an old timer drawing on them with a paint pen. Few more days of cutting and re glassing and somewhat more subdued rolling chocks went back in the water. Probably less effective than version one, but didn't need full thruster to turn....

Seems the best bang for a buck is what they call a Portuguese chock here. Basically some thick steel 3 times wider than the keel down the middle 75% of the boat. Don't know if it's a local colloquialism or it's actual name. Nine times outta ten it's a big chunk of mild flat bar wheel abraded pre prime from farwest down in Eugene tapered on the ends and welded to the keel. Then it's usually rolling chocks of some variety, followed with some paravane poles and paravanes like the ones kolstrand has listed.

Can't think of an ARt that is still in operation that's not been removed or turned into a gear locker....

Just want to emphasize it's incremental gains with hopefully mild trade offs, nothing passive will be a silver bullet.

Do a quick personal example. My family had one of the last round bilge seiner in existence with no rolling chocks. Probably one of 300 with a smooth bottom. Mainly due to the fact that my grandfather didn't leave a specific area he fished with it and had other boats for other areas. As it moved down a generation, ol uncle decided it needed something to slow the roll. So we pulled a good jig off a sister ship that most folks agreed was the best set fit. Made some up and slapped them on. On the way back around a cape towards out house my crewman exclaimed "much better" followed by my little brothers "yeah and still bad". It was never going to make a honda civic a one ton diesel, it was just a bit better.

If it were my money I'd start with the two types of passive rolling chocks and then start to wrap my head around some poles and paravanes. Wouldn't be terrible hard to fit and retrieve a set.

 

This boat did have rolling chocks in the past, but they were removed. At least, that is what the old survey suggests. Was it removed because of the modifications, or after, I do not know.

So, if not rolling chocks, can it be ' bilge keels ' ?


I went to Astoria, OR today to talk to the yard there. They have welders on site, who have experience with this type of work. After my detailed description of the problem, we agreed that we will start with the I-beam extra weight mounting. Preferably using the lead ingots I have inside the bilge already. If that can be removed, melted, molded and mounted at the bottom, I suspect will serve better. I need access to the bilge anyway to remove the existing rust there.
The next step could be adding weight one by one to the keel tanks bottom area. Easy to mount, easy to remove, if necessary.
As the last resort, we can remove the air tank at the stern and see what happens. It is extra weight at the wrong side of the boat. Will the missing lift be compensated by the already added weight on the I-beam and keel tanks, nobody can tell. I really don't like that air tank there. It is ugly and I am convinced it was the main reason of terrible handling of the following swells during my last trip.
This whole process will take years, because I can haul it out only once a year.
Paravans and such are not going to work for me. I am too old to be able to handle heavy stuff in nasty weather.