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.

 

Hello Gents.
I hope I can revive this thread again and get some answers to my dilemma.
My haul out at a DIY yard is approaching (Aug. 1) and I have not given up on the idea that I will try to find a solution to my boat's rolling problem. It seems to me that one thing I can do is to make measurements. Without any type of numbers, no welder, no fabricator, no NA will talk to me seriously. If you would recommend to measure and get data of the hull, what would it be? The boat will be on hard for few days for a paint job.
Ad Hoc recommended an approach to mount weights gradually to the bottom. His suggestion was to do it at the lowest section of the hull, where the ballast tanks are. To do this, I will need to drill holes from outside and install bolts for mounting of the weights. I am not confident about doing this without damaging the tanks. Honestly, I do not know how the bottom of those tanks are built? If there are mounting holes at the bottom, soon or later those might leak and flood the tanks from outside. Ad Hoc's approach would allow the gradual weight increase, so the right amount of weight could be found for the hull. If those bolts for mounting were in place, I could do the diving/mounting myself, even if I am getting old for diving already. Instead of drilling, it is possible to weld these weights on the outside surface, but this would require several haul outs, since it is hard to tell how much weight is the ideal.

Another area for weight mounting is the I-beam mid section. You can see on the photos that the bow section of this beam already has a mounted weights on both sides. I suspect it is a large piece of steel block. It is mounted by bolts at both ends. I have no data on this, so I cannot tell how heavy these weights are. I suspect it was installed by a yard, using forklifts.
If I decided to mount weights on the remaining free surface of this beam, I could do it by drilling holes in it and mount lead ingots there. Drilling on the beam has no danger of doing any damage, but having too many holes on it, might not be a good idea. Although, the ingots can be purchased everywhere, I could not decide what size would be the best? The ones I see online have a standard block size of 2"x4"x8" and those weight around 26 lbs. I am not sure how many of these can be placed on that beam, if the thickness of a block is 2" I could use at least two layers, or maybe three, of them on each other. How many total, I have no clue. I need to measure that area carefully. Another question mark is the size of the ingots. The standard block is given, but custom blocks can be ordered, too. There comes the rub. I can lift the standard block myself and mount it. But this will require lot of blocks and drilled holes. If I order custom, but larger and heavier blocks, I might not be able to mount those alone. I will need to hire help, perhaps a forklift as well. That increases the cost for this job. If I do the regular size blocks, I might need several layers on each other, which could increase the drag while underway. Of course, without knowing the available space on the beam, these thoughts are just theoretical.
Per the old survey I have, it says I have 5000 lbs of ballast installed. I suspect this is the sum of the lead inside the bilge area, the weights on the beam, and the ballast tanks. Those tanks can hold around 450 gallons of water/fuel total. That is the only way I could come up with the 5K lbs ballast.

The next area I would need to measure is the keel fin mounting section, if that is what I decide to do. I think I have mentioned that this boat already had rolling chocks mounted at one point. Did it work, or not, I do not know. Was the hull originally built with the chocks, I don't know. Was it removed, because it did not do much on the rolling problem, I don't know. Was it removed by the last owner because of aesthetics, I do know. Either way, I can still see the welding marks at the chine, where the chocks were welded on. So, that would be easy to redo, if that is the decision. The length and width and the angle of the chocks can vary, but a good welder with experience with chocks would be able to figure that out.
The next option is the smaller, but deeper fin type of bilge keel. The first photo I have previously posted here of different boats shows what I am referring to. I suspect, these fins can be pre-fabricated, as long the shop has the measurements. Perhaps, these fabrication plans can be purchased from a NA and can be given to a welding shop to make them? If this can be done, a welder can mount those onto the hull at a haul out. The question is; what measurements do I need to give to a welder/NA to be able to make these? Or, does it have to be done onsite, boat hauled out, and approach the installation gradually piece by piece?

Please, help me out with my dilemma. Thanks.

I'll attach few more photos for your pleasure....

The first two are about a keel-shoes solution I would like to have installed. Would it work? I don't know, but it is easy to remove later. I suspect, in my case, these should go to the lowest possible midsection of the hull, above the ballast tanks.
The other pictures are just to show the existing weight on the beam and hull shape.

 

Apologies for being MIA, I've been extremely busy.

I think, really we need a baseline of what the vessel is, in terms of the roll period.
Are you able to make a "rough" estimate of the roll period...?...and are you able to "roughly" estimate, the angle of roll she experiences, when subjected to a modest beam wave, and how long does it take to restore back to upright?

I also think, given your limitations, re: costs and time for "simple" mods, it will be tricky to get to the bottom of everything and a remedy which fits into your ability to do the work, mostly yourself and without incurring costs for constant hauling in and out. So, perhaps, just perhaps, a course of action maybe this:


Remove that 'blip' aft, and then extend the natural lines of the hull aft, like shown. Try not to make it too fine, a nice lazy curve that would gain back the buoyancy 'lost' by removing the blip.

Then add a bilge keel, shown in blue, which is made from 2 plates space around 100mm apart at their base, where it is welded to the hull, with some simple internal ribs, which allows for plug welding to "join them" together, so it has stiffness/strength. Make it a very simple symmetrical shape, nothing fancy needed.


Lining the plates by eye, by standing in front of the bow and cast your eye along where the natural curve of the hull plating is going. Scribe that and use that as your rough guide to where to locate the bilge keel. To be as far "outboard" as possible will help...so 2 locations noted, merely for ref.

Then on the base of the bilge keel, have a thick bar that allows for bolting on ingots to add "solid" ballast.


This way, you can experiment with adding weight by 1, 2 or 3 ingots, or how ever many you think will help.

But you need to remember, adding weight will also influence the trim.
So, note where/how your vessel trims, under normal conditions.....then note the location of where you wish to add these weights. Make sure it is 'central'...to this location of level trim, between the bow and stern.

Otherwise you may end up solving one issue and creating another.

 

Ad Hoc!
Nice to hear from you again and I really appreciate your notes and suggestions. Even I can understand your thinking and I really like what you described.

Couple questions:
- How wide the bilge keel should be, how deep should it go downwards?
- This boat did have bilge keel at one point, but it was removed. One of the photos shows the welding marks, where it was mounted. Can that same location be used again for your version?
- Would the cut off the blip interfere with the rudder components, or mounting? Can the rudder be left alone, as it is?
- I wonder, if the blip is cutoff, the original hull would reappear there? If the blip was just simply welded on the top of the existing hull, it could be the case. If yes, maybe no addition will be needed? Is there an instrument, which I could use to ' see ' under the blip? I have mentioned before, I have never opened this blip. There are two outlets inside the ER for port and starboard, with a shutoff valve, but I never touched those. I suspect the blip is just an air filled tank. I also suspect it added weight to the stern area. (Now that I think of it, when I look at this section inside the ER, it looks like the original hull surface from there. I do not see the flat bottom shape inside the ER towards the aft.)

Regarding to the roll period test, the answer is yes and no. I am on the Columbia river, where there are no following wakes. If I wish to go out to the ocean, I have to sail two days to get there. Weather permitting, I could run an app on my tablet, which can register some movement, but it is not scientific and it was not made for NA calculations. It can help to get the idea of the rolling, but it will not be highly accurate. It was recommended to me by another boater, who used it for the same purpose. I have to admit, I was not able to figure it out completely, how to give good rolling results. The App had bugs, even in the Pro version, but it has been upgraded multiple time since last year. I will try to get something out of it. What I did, and can do again, here in the marina, is to roll the boat, while the App is recording and see, if I can attach the results here. This is what the other guys were using it too, prior bilge keel installation. Maybe it will make sense to you, because I am a bit lost on this roll, recovery, upright, etc. terms. The name of the App is Physics Toolbox.

 

Firstly look around the Marina, and see what size length and depth they are for the size of boat, and “guesstimate” what yours would be assuming the same.
As a first hit, that may be a suitable guide.

Well, if you think of it in “simple” terms...the farther away from the centre of rotation the better. As this creates more lever, and hence more of a resisting ‘moment’. So look at where the existing weld marks are, and if you placed a bilge keel there, does it “look” like the farthest distance from the centre of the hull - without being too close the the static waterline??...that would be a simplistic guide.

Well, that’s where eyeing/looking at where the rough red lines, following the existing hull line would help. You may find that it does not interfere with the rudder mounting or it does. If it does, just leave what is exposed, since it is already there…does that make sense? Then you can leave what is already there…don’t make work for yourself.
But just make sure you don’t remove buoyancy, since the existing blip helps – from what I understand, in terms of the trim and waterline level.

You could drill a small hole and place a fibre optic endoscopy camera of sorts.
Fill/weld the hole afterwards.

You could try a very simple basic test.
If the water is warm….you could have 1 or 2 large people stand on the deck edge, roughly midships, with you standing on the centreline and close to them as possible. Then ask them to both jump off at the same time – the vessel will oscillate back and forth until it comes to a rest. Time each successive roll cycle…and from that you can get a very “rough” roll period. Or jump onto a jetty…if that also works/able too?
Does that make sense?

 

Yes, all makes sense. Thanks again.
I will do the roll test and post it. It will be only me, but I think I can get that data.

There is only one steel boat here. This is a small marina.
25' Tug Yacht Boojum - Kasten Marine Design https://kastenmarine.com/boojum25.htm
It has bilge keels, but the owner is never here, so I cannot climb on it.

 

This way, you can experiment with adding weight by 1, 2 or 3 ingots, or how ever many you think will help.

But you need to remember, adding weight will also influence the trim.
So, note where/how your vessel trims, under normal conditions.....then note the location of where you wish to add these weights. Make sure it is 'central'...to this location of level trim, between the bow and stern.

Otherwise you may end up solving one issue and creating another.[/QUOTE]



Ad Hoc

Please, help me to understand your point about the trim.
Am I looking at the waterline? Or, looking at the Pitch degree of the boat (it is showing 3 degrees up at the bow now in the marina). Or, I have to mark something now, before I add things? I am not sure what am I suppose to do during this ' adding weight ' process.
Thanks.

 

Ok, a "typical" boat here as an example.



Boat floats level, shown by the red waterline.

If you added a weight here, she would float like this, "roughly":


The weight being aft, she will trim by the stern.

Or up fwd:


So, when your boat is floating "normally"....take same weights and place them aft and fwd, notice how much she trims..and then try to find the location where adding the weights, all she does is sink down, and not trim.
Make a mark on the side of the boat...as this is then "roughly" the centre point for you adding weights below, on the bilge keel...assuming this is roughly where you also place the bilge keels too.

 

Got it.
Right now, the Raymarine EV-1 sensor shows 2-3 degrees up at the bow. This is when the boat is in the marina and does not move. This sensor is in the PH now, but I think it is fairly accurate. However, I do not know, if this 2-3 degree was planned during the modifications?
Perhaps this few degrees higher bow is the result of the stern blip addition? We'll see the trim, once that blip is removed.

Either way, I understand now the goal and when I add weights, this will be carefully observed. If the ingot mounting area is pre-drilled, or pre-bolted, I do not mind to dive and add them one by one. It will take time, but I have time plenty.