42 M/Y Build - Questions

Discussion in 'Boatbuilding' started by Scarab, Sep 6, 2014.

  1. Scarab
    Joined: Sep 2014
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: North Carolina

    Scarab Junior Member

    I acquired a newly built 42' fiberglass hull, that has bulkheads, fuel tanks and engine beds. It also came with a set of plans.

    I want to complete it and I have no boat building or carpentry skills.

    Within the next month I plan to take a basic boat building carpentry class and another class where I will build a small boat using those skills. So, before I start the project I will attain some know-how and I'll have a small dinghy that I built myself to practice and test on.

    I know I'll have to hire out some of the work, but I want to do as much as I can myself. I have a limited budget but I want the completed vessel to be aesthetically pleasing, high quality and fully functional.

    I'll have a lot of questions and my hope is that I can ask them here and get answers from knowledgeable people. Many of my questions will probably seem stupid to knowledgeable boat builders, but we all have to start somewhere.
     

    Attached Files:

  2. Scarab
    Joined: Sep 2014
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: North Carolina

    Scarab Junior Member

    The boat won't have a flybridge, but it will have a fully covered cockpit.

    So, my first question is....

    Is it better to complete the exterior fiberglass or to finish out the interior first?
     
  3. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 472, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Not to burst your bubble, but there's absolutely nothing about a 42' power yachts build that can be handled on a "limited budget". Just look at some good marine diesels, say a pair of 300 HP D4's which run $25k each. You might find some good used ones for 18K, but will they both have the same wear and be matched performance wise . . .

    Maybe I'm jumping to conclusions when I shouldn't and your budget has sufficient room for a 1/6 to a 1/2 (+) million dollar yacht.

    To specifically answer your questions, if you don't finish the outside first, get something over it, even if it's just cheap house paint (easily removed), so you don't have UV and other damage, when it's time to actually complete this part of the project. If it was me, I'd start on the fiddly, out of sight stuff first (inside), because you'll still be learning how to handle the techniques and materials, so these places can live with these than perfect finishes. As you acquire the skills, you can move onto the finish work. You'll want to get the engines and equipment in pretty quickly as these will need, plumbing, wiring, electronics and assorted fabrication, before they get sealed under decks or closed up into their respective spaces. The finishes take the most time, particularly if you want it "right", so do the dirty work first and put the lipstick on last.

    What is your budget for this project, if I might ask? Not for nothing, I'm a pro and I wouldn't take on a project of this size, without a crew of skilled help. I currently have a 65' project underway and wouldn't think of attempting it, without a 5 or 6 man crew in the trenches with me, unless I was just looking to make a career out of it. My point is the shear volume of effort it is, to finish out a yacht of this size, let alone as a novice. Don't take offense, it's just a bit surprising that's all. I hope you can do it, she'd be a pretty babe when completed. I'm glad I will not have to handle her fuel bill.
     
  4. Scarab
    Joined: Sep 2014
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: North Carolina

    Scarab Junior Member

    Thanks for the advice.

    It's going to be an electric hybrid. I want to power it after the construction is complete so I can take advantage of whatever technical advances that take place with battery storage and electric motor enhancements between now and the time it's completed. I'm aware of the costs associated with powering the vessel.

    It shouldn't be difficult to power it after completion as the design calls for the motors below the cockpit deck.

    I know it's a huge job, and I know it isn't going to be cheap. When I say 'limited budget' let's say it means that I have between 5 and 10 thousand dollars per month to work with until it's complete, but I want to do as much of the work myself as possible both to reduce costs and participate in the build/pride of ownership. I have the ability to work on the boat full time until it's completed.

    I should also add that the construction will take place inside a covered building.
     
  5. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 472, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Making that particular hull form an electric hybrid is just not even close to reasonable. That's a 700 HP hull. You could run it on less, but lets face it, this isn't an efficient hull with limited power, meaning she'll do everything poorly (lousy steering, handling, energy consumption, etc.). You'll need to price this idea out, as it'll be way more then a set of diesels and ten times as much as a couple of big block Chevy's.

    Also, I don't think you understood me correctly. You'll have to install the "systems" first, other wise you'll just have to cut up what you've just installed, to fit things in, which generally isn't a wise investment in time and materials. It's much easier to fit plumbing, electrical runs, etc. while the boat is open. As to fitting engines last, well you still have the same problem, running the systems to and from them. So, you'll build cabinets and countertops, just to rip them out and install plumbing and electrical? This is why the systems go in first, so you don't have to rip anything out. You'll still have to drill holes in newly finished stuff, but this beats having to wholesale knock things apart, because you've got four 4" exhaust hoses to run (as an example). It's a bit like building a complete house and waiting to install the floor joists, until the end of the project.

    Go ahead and price up generators for 500 KW, plus a few battery banks to support a load like this and compare it to a twin diesel or even a couple of 454's.
     
  6. Scarab
    Joined: Sep 2014
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: North Carolina

    Scarab Junior Member

    Actually, it's a 600 hp hull. As I said, I'm aware of the costs to power it.

    Not to burst your bubble, but I came here looking for boat building advice, not financial advice. I already know that most people know the price of everything and the value of nothing.

    However, I gather from what you're saying that I should do the electrical and plumbing systems before I begin any 'construction'.

    That makes sense and I thank you for the info, and I also thank you for reminding me why I left Florida :).

    I'll post again in a month or two after the electrical and plumbing are complete.
     
  7. rustybarge
    Joined: Oct 2013
    Posts: 533
    Likes: 3, Points: 18, Legacy Rep: 37
    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    Just for reference a band new marinised cummins 6bt 330hp engine is $15k without accessories; (it's called reconditioned to get around the US emission controls) You could get alternators etc etc second hand.

    A single 330hp engine would probably push your hull at 15-18kts max(8-10 tons:guess with s/screw), but give you a very economical 7 kts cruise at about 1500revs/1.5-2 gals/hr

    ...those numbers could work out nicely! :)
     
  8. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 472, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Sorry about the assumptions, in regard to the financial aspects of the project. Most don't know what they're getting into, which was my fault.

    Pushing that hull at 7 knots wouldn't be economical, you'd be dragging a lot of transom and deadrise. It's a twin setup for sure, unless you employ a hefty single outdrive, you'll need these twins to have reasonable maneuverability. Hell you could also bracket, well mount or transom hang a couple of Black Maxes too.

    Have a good look at the "electrical draw", by preforming a full up wattage requirement count. This will give you a picture of the hybrid situation. Unless you have a huge electrical need, where you can justify 50% or more in non-propulsive applications (refrigeration, A/C, etc.), making hybrids work, particularly on a yacht of this size and configuration is difficult to justify, both financially, plus in terms of efficiency and range.

    What you really need is a solid plan, as shooting from the hip on a project this size will just get costly quick. You'll need to know what equipment you'll have aboard, what systems, engines, generator(s), refrigeration, instrumentation, controls, electronics (to some degree), HAVC, general low and high voltage systems, general plumbing, etc. Some of this you can "engineer on the fly" but much of it will be application specific.

    You'd be well advised to bring someone on board for consultation at the very least, possibly a rudimentary plan for the various systems. This is cheaper in the long run, rather then just trying to "wing it".
     
  9. rustybarge
    Joined: Oct 2013
    Posts: 533
    Likes: 3, Points: 18, Legacy Rep: 37
    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    It's very hard to see from the photos, but that looks like a hull with very little deadrise at the stern, but with a fine bow entry. There Also appears to be a keel which should make it track straight at displ. Speeds.


    Any more photos of the hull?
     
  10. Scarab
    Joined: Sep 2014
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: North Carolina

    Scarab Junior Member

    The hull has a small keel and should handle fine in the 6 to 10 knot range.

    There are two ideas for the vessel. The first and most desirable will be two large electric motors that will get it on plane and push it 30 to 40 kts. Without going into details, this might be achievable by fabricating what amounts to a small hydro-electric power plant in a swim platform. I'll be testing that on the 12' skiff.

    If that isn't achievable, the boat will do 6-10 with two smaller motors, a generator and a roof full of solar panels.

    Likely we'll end up somewhere in between.

    Because the tech for electric propulsion is rapidly advancing, I want to finish out the interior etc before I make the final decision on exactly how to power it.

    Diesel or gas engines are the least desirable option and will be avoided.
     
  11. FMS
    Joined: Jul 2011
    Posts: 607
    Likes: 19, Points: 18, Legacy Rep: 227
    Location: united states

    FMS Senior Member

    Work all the details out on paper for a system that you could afford today before you start. When you have to retrofit and work around other things, it takes ten times as long. Often technology doesn't come as fast as you think. This way you have a plan that's real and don't end up with something that never will be. And if new technology comes along making the planning obsolete at least the planning isn't itchy.
     
  12. rustybarge
    Joined: Oct 2013
    Posts: 533
    Likes: 3, Points: 18, Legacy Rep: 37
    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    A 42' boat of about 12 tons will need twin 300hp (600hp) to max out at about 20kts. You will need more than 1000hp to bust through 30kts.

    How many kilowatts of electric power is that?
    How much will it weigh?
    Are you going with a nuclear power plant?
    Is this a troll? :):):)
     
  13. Scarab
    Joined: Sep 2014
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: North Carolina

    Scarab Junior Member

    Not a troll.

    The boat was designed to do 40 knots with 600 hp.

    With the increased torque electric provides, the hp requirements are lower for the same results.

    Jet drives will provide a massive surge of water flow, which should be able to generate from 30 to 50 KW of hydro electric power while running and reducing speed by only 5-10 knots.

    Here's the thing boat builders forget....and it's the question that provides the answer...

    Why does it require 600 hp to move a boat 40 knots and only 50-75 hp to move a car the same speed?

    Answer that and you'll understand the entire concept.

    Anyway....I'm outta here to go get started on my boat. I'll post again if I have any questions once the electrical and plumbing are installed.

    Regards.
     
  14. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 121, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Scarab... Befor you go and start your work, you should search out numerous threads on this forum which have covered electric propulsion ideas ad nauseam... There has been a lot of great information shared, by professionals and electricians, and naval architects, General Electric enthusiasts in general.

    As I was interested in a similar idea, when I looked into the feasibility of it, it's just not there. The costs of doing it properly are astronomical, far more than the carbon creating engines, and lifetime supply of fossil fuel to feed it.

    Then there is practicalities, such as having no payload carrying capacity, because just about your entire boats displacement is used up to carry the generation capacity and energy storage needs. In other words, the boat becomes a floating battery, or floating power station with no room for anything recreational. Energy density is the problem. Fuel burning engines and fuel tanks filled with fossil fuel have a very high energy density.

    I know a guy here in Australia, who went down the electric propulsion route and fitted 2 electric drives to his 44ft catamaran. The entire system was so bad for so many reasons, he ripped them out and replaced them with outboard motors after the boat was damaged in a storm and had to have a major refit.

    Like i said, this idea has been covered to death, every week another guy looking to implement the same idea comes along here, the practicalities and the economics just don't stack up. Should you attempt it regardless, you will be wasting a hell of a lot of time and money on boat which no one will buy when you've realised your mistake... Youre not the first, you've been warned.... Do your homework...
     

  15. Scarab
    Joined: Sep 2014
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: North Carolina

    Scarab Junior Member

    When Robert Fulton invented the steamboat, the sailboat builders told him it would never work. Same thing happened when the Priestman brothers put together the first motor boat. The first sailboat builders probably got laughed at by the rowboat guys.

    Anyway, perhaps my concept will work, perhaps it won't. I'll know the results of my years of homework soon enough.

    If it doesn't work, I'll throw a couple small electric motors in it and happily putter along at 6-10 knots with a generator and solar. I Know for a fact that works.

    This is why I didn't want to get into conversations about power on this forum. All I came here for was info that would help me put together the interior and exterior.

    Adios for now....really.

    ======================================================
    "The fear of meeting the opposition of envy, or the illiberality of ignorance is, no doubt, the frequent cause of preventing many ingenious men from ushering opinions into the world which deviate from common practice. Hence for want of energy, the young idea is shackled with timidity and a useful thought is buried in the impenetrable gloom of eternal oblivion."
    — Robert Fulton


    "My steamboat voyage to Albany and back, has turned out rather more favorable than I had calculated. The distance from New York to Albany is one hundred and fifty miles; I ran it up in thirty-two hours, and down in thirty. I had a light breeze against me the whole way, both going and coming, and the voyage has been performed wholly by, the power of the steam engine. I overtook many sloops and schooners beating to windward and parted with them as if they had been at anchor. The power of propelling boats by steam is now fully proved."
    — Robert Fulton

    Quotes by others about Robert Fulton:

    What sir, would you make a ship sail against the wind and currents by lighting a bonfire under her deck? I pray you excuse me. I have no time to listen to such nonsense.
    — Emperor Napoléon Bonaparte
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.