Rolly custom steel motorboat

Discussion in 'Stability' started by LeoKa, Sep 2, 2024.

  1. LeoKa
    Joined: Sep 2024
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    LeoKa Junior Member

    I was sent here from another forum, suggesting that some of you might be curious about my situation.
    I am the 4th owner of a custom steel boat. The original builder purchased a Bruce Roberts motorsailer kit (52-54') and constructed the hull. He chose a CAT 3306 engine (220 HP), which is much larger than what the BR plan was designed for.
    Out of money, or time and energy, he sold the hull. The second owner finished the boat, by creating a big and spacious upper structure. This idea has messed up the original stability and corrections had to be made. They hired a naval architect, who had made several suggestions. First was a long beam at the bottom of the keel from front to back. Next, two fuel tanks (200 g each side) and extra weight mounted onto the beam. Next was filling the bilge inside with lead from midsection forward to the bow. Lastly, an air filled tank was added to the hull at the stern. See attached photos.

    As of now, the boat is very tender. The squatting has been mostly eliminated. (pitch is between 3-6 degrees at the dock). I was not able to test properly the rolling periods, but it is not snappy. Takes a while to calm down.

    Last year, I sailed from the Puget Sound down to the Columbia River to a new marina. It was a two days trip, since the cruising speed is around 6 knots. I was heading South strait to make to Newport WA as there was not an option to anchor out safely anywhere. I had NW winds and NW swells all the time. The boat did not handle well the following seas and lot of things inside got loose. Partially it was my fault, since I did not secure everything well for the rolls, which reached 20-22 degrees. Yes, it was a mess.

    My question to the members here, after studying the pictures, is there anything can be done to improve the sailing comfort? Speed is not my concern, since the boat is already slow. The boat handles head on waves quite well. Pitch does not bother me. The roll however, made the trip very uncomfortable and made me nervous occasionally.

    It was suggested to try different things. A major alteration is not an option, so active gyro is not a solution. However, rolling chokes, bilge keels, steading sail (with extended mast), even rolling water tanks; were on the list, to make the sailing experience better.

    Any input is appreciated.
     

    Attached Files:

  2. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Hello LeoKa, welcome to the forum

    So, the images posted above and your comments on:

    Are based upon the boat in the modified condition, as noted above?
    In other words, all those "suggestions" by the NA were implemented when you sailed down Puget Sound and had the not so pleasant trip?

    We need to establish the fundamentals first before moving forward.
     
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  3. LeoKa
    Joined: Sep 2024
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    LeoKa Junior Member


    Correct. Those events must have been about 20 years ago, or longer. The boat was launched in 2000. I bought it in 2018.
    Again, I do not have solid info about the history of this boat. No documentation is available, besides some very old receipts.
    What I know comes from other people, who remembered things.
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Aahh..ok, that puts things into perspective now.
    Since weight growth is inevitable on any boat and over 20 years probably more than realised and most likely, not in an ideal location either....i.e too high up!

    So, it all depends upon how much money you wish to spend to investigate and correct the tender/rolling issues.

    So, the first question is, can you, or would you hire a local NA to conduct an inclining experiment?
    This is the establish exactly where the VCG and lightship is now, after 20 years of bits and pieces being added without too much thought.
     
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  5. gonzo
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    gonzo Senior Member

    You could add simple passive systems like bilge keels or flopper stoppers. A better system is a gyroscopic stabilizer. They are getting much smaller and affordable. That is a very tall superstructure. Also, the hull has a rather deep vee. You couls also do major surgery and cut off the bottom of the vee and have a flat bottom, or modify the superstructure to make it lower. Finally, uncomfortable motion is very relative, so you should quantify it before talking to an NA.
     
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  6. LeoKa
    Joined: Sep 2024
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    LeoKa Junior Member

    Possibly.
    However, it all depends on the future plans I might have. Me being retired limits ideas.
    Honestly, I have no idea what a NA charges and what would that accomplish? 40 years ago I would certainly want to make this boat more seaworthy. Like many of us, I also had big plans to cross oceans. Today, I look at things differently.
    Few thousands of dollars for simple modifications can be considered in 2-3 years. 30-50K dollars definitely not. If that is the price, I would just continue use it as my live-board home.

    I tried to track down the NA who was involved in the changes back then, but I got nowhere. Some people know him, but I was told that he does not do anything anymore.
    I talked to another boat designer, who knew a little about this boat and he suggested to leave alone as it is.
     
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  7. LeoKa
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    LeoKa Junior Member

    I have no desire to do major modifications. If that is the only alternative, I will just sell it at some point and move on.

    20-22 degrees to both sides felt uncomfortable to me, because the roll was quite accelerated. I had to hold on to something all day.
     
  8. comfisherman
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    comfisherman Senior Member

    Id probably be going for decent set of bilge keels or rolling chocks, and then add flopper stoppers as a secondary.
     
  9. LeoKa
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    LeoKa Junior Member

    Do I need to find a yard specific to dealing with chocks and bilge keels, or any serious yard would be able to design and install those?
     
  10. Ad Hoc
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    Ad Hoc Naval Architect

    Thanks for being more candid, it helps.

    Ok..so the issues relating to the tender nature and rolling, are the VCG and the hull shape. By hull shape, I refer to the beam. Also your comment out following seas, is potentially an issue too.

    The following seas:

    The pod structure shown here,

    upload_2024-9-3_10-27-36.png

    adds a lot of buoyancy, which is likely to correct the trim/squat you mention. But in doing so, it adds buoyancy in the location that is not suited in following seas. Since once a wave from the stern, approaches the transom, it (the hull) has more buoyancy aft, and as such, is lifted by the wave. So as the following wave moves from stern forward, it picks up the boat – aft – so you pitch down by the head – which can be exacerbated (and dangerous) if the bow is presented with a trough of the wave….she can nose dive and broach.

    The only options/solution in this is seamanship – not withstanding changing the hull shape, which is not going to happen. You’ll have to keep an eye in following seas, note the path of the wave and try to ensure your speed does not match the wave speed or any where near its speed by 70% and where possible be quartering seas to it, and be ready at the helm.

    The rolling:

    Lowering the VCG is a must, where possible. Can you relocate heavy items to be lower in the hull?
    Can you add any more lead in the keel?

    Also, you may want to consider – but possibly unsightly to the eye – adding blisters above the water line to increase the beam at the gunwales?

    Some thing like this:

    upload_2024-9-3_10-27-59.png

    And finally, adding bilge keels port and stbd.

    upload_2024-9-3_10-28-58.png

    This may all fit into your budget and possible longevity for the hull.
     
  11. LeoKa
    Joined: Sep 2024
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    LeoKa Junior Member

    Wow, what I great info! Thank you.

    1/ What are the blisters at the gunwales?

    2/ The bilge is full with lead already. Additional weight could be bolted to the bottom beam on each side, behind the existing added weights. How much? I don't know.
    3/ Bilge keels are really my first desire.
    4/ Seamanship. Absolutely correct. As I described, my trip down to Columbia was not ideally executed. I was in the hurry and not planned well. Going strait down was not smart to handle the following swells. I should have gone further out from the shore and tack. With slower speed perhaps, finding the right angle, I could have handled the sailing much smoother. Lesson learned.
    Just few weeks ago, I took the boat to the yard in Ilwaco, WA. From Astoria OR I had to cross the river delta, with a bit similar situation about the swells coming in from the ocean. Not only I steered the boat in a comfortable angle, but also slowed my speed down significantly. The result was much safer crossing. Nothing broke, nothing moved inside. Yes, it took 3 times more time to cross, but it was worth it.
     

    Attached Files:

  12. Ad Hoc
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    Ad Hoc Naval Architect

    In cross-section, a shape like this:

    upload_2024-9-3_11-6-14.png


    Indeed, something like this:
    upload_2024-9-3_11-6-45.png

    You could experiment with adding blocks, which cover small section of the keel, and increase the amount after each "test"..
    Could be costly since you have to keep hauling out the boat. Unless you pre-drill holes, ready to accept another block and just dive down and fit it.
    But you also need to be mindful of not creating too much trim too, so needs to be added roughly in the location of the LCG, in lightship, and then move on from there, either side in each amounts.
     
  13. LeoKa
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    LeoKa Junior Member

    Pre-drill holes can be tricky. The area you are showing is the fuel tank section. The beam is ok for more weight, but the fuel tanks will require a careful planning.

    I still have my diving gear, but cleaning the barnacles made me hate diving in cold waters.
    I do plan to haul out every two years, so it could be something I could manage.
     
    Last edited: Sep 2, 2024
  14. LeoKa
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    LeoKa Junior Member


    Do I need an architect for this, or a decent yard with proper shop can install it?
     

  15. comfisherman
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    comfisherman Senior Member

    There were some decent yards in astoria, as well as down in yaquina. Admittedly it's been 10+ years since I was on a project in either place and with the ups and downs I'm not current on who's doing steel work. Rolling chocks are an easy project, as would trolling poles for flopper stoppers. Would think most metal shops could do the work.
     
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