Putting it all together.

Discussion in 'Boatbuilding' started by LP, Jan 7, 2007.

  1. LP
    Joined: Jul 2005
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    LP Flying Boatman

    Thanks Dave! I figure I'm sitting around 1000 pounds. I bit beasty, but I believe it rides better for it. I read your thread. Interesting project.

    Here is another short video.
     

    Attached Files:

  2. lumberjack_jeff
    Joined: Oct 2010
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    lumberjack_jeff Sawdust sweeper

    Outstanding! That's a gorgeous boat.

    Very well done, and that motor sounds great.
     
  3. Yellowjacket
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    Yellowjacket Senior Member

    You need to double check your tach and make sure you aren't turning that motor more than 6,000 rpm. If you are exceeding that on a regualr basis you will burn up the rod big end bearings. This is the same powerhead that we use in the Merc 44xs in APBA racing and the first thing that you do to that powrhead is hone the rod big ends to increase the clearance. Once you do that you can reliabliy turn the motor to 7k and more.

    Mercury used to build the 44 cubich inch motors with more clearance, but that made the engine noisy at low speeds and they wanted the customer to feel that the motor was really smooth, and it is with the tighter rod clearance. But that limits how fast you can turn it without opening the big end rods to set the clearance.

    I would think your boat with a 50 should do a bit better than 30 mph, if it has the right prop on it. If you are indeed turning more than 6,000 you need to get a prop with some more pitch, or just pull back the throttle and keep it under 6k...
     
  4. LP
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    LP Flying Boatman

    Great information YJ!

    I'm still trying to figure out a few things with the boat and motor. I'm not fully reliant on the tach, yet. I've calibrated it with all available information. Some of it word of mouth, but checked out with other sources. I'm thinking of getting a timing gun with a tach option on it to verify engine RPM. I will limit revs until I know for sure.

    I had the choice of a 12" pitch or an 11" pitch and went with the 11" because I was concerned that the boat was heavy and would not perform. The 12" is a smaller diameter, but I will change it out to see if the prop pulls up the speed and lowers the revs.

    FYI, this is an older engine. It is a '72 so I don't know if that makes a difference or not.
     
    Last edited: Oct 23, 2012
  5. LP
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    LP Flying Boatman

    History of the design.

    Now that the boat has been wet and it didn't sink or need 200 HP to go anywhere, I can confess my sins in it's developement and build. The design inspiration was taken from How to Build Wooden Boats by Edwin Monk. Page 45. I know several of you have this book. Ed's design is called Sunray. Attached is a de-rezed photo from the book. I hope this doesn't violate copyrights. It will be removed if needed.

    IMG_1874.JPG

    I was just rereading the description and had my bubble burst. An F-Class engine was supposed to push it around at 30 miles (per hour I assume). The original design is still faster than mine. :( My quick search on F-Class engines didn't give me any useful information though it did lead me to this interesting link. Cool Antique.

    http://www.boatracingfacts.com/forums/showthread.php?9623-Mystery-1930s-14ft-F-Class-Mahogany-Boat

    To continue; Sunray is 16' 6" with a 5' beam. I was wanting a bit more boat when I was creating my design. A convenient 2" was added between every station to make the my design an even 18' in length. I must have also manipulated the stem because as the boat sits right now, she is 18' 6". I have a mystery 6" on my hands. I guess I'll keep it. The original design also has a warped bottom bottom with a hook that was common for the day. At the point of deepest V in the original design, there was about 10 degrees of deadrise. I took this point on the hull and extended that deadrise the full length of the remaining hull. Not a serious departure from the design, but also a conservative change IMHO that should apply a modern condition to a classic hull. 10 degrees should give decent lift potential and the straight run should give it good speed potential. Additionally, the added bouyancy in the stern would be benefitial for floating a heavier engine.

    At the time, I was extremely eager to start the build. I was a few months completed with my 16' sailboat and was eager to build something else. I used Gerr's Elements of Design and I was off like a lunatic with the next build. Researching my files, I had choosen to build the hull with Gerr's additives for speed. I scanted the hull with Gerr's max of 45 kts. This place the keel dimensions at 1.5" x 3.7" and a wise boat builder would have stuck with those figures. I left the timber at 1.5" x 5.25" as it came from the lumber yard. The deadrise ate up a portion of the excess material and a nice radius on the top ate up some more, but I still had an extra 1" square of material. I may be glad that it is there and I'll explain later.

    Monk's plans for Sunray show the chine logs as almost triangular. I took this to heart when to came time build mine. I took the cross-sectional area defined in Gerr's scantlings and converted them to a trangular shape of the same cross-sectional area. This was most convenient as it allowed for minimal fillets at the "chine logs" and the internal glass sheathing wrap nicely over the logs.

    Gerr's scantlings on the bottom plank with speed adjustment came to 0.5". I don't recall, but I may have made an allowance for material removal in the fairing process. I may have added as much as an 1/8" to the bottom plank. I also chose to cross-plank the hull. I would not do it this way again. I chose this path because I didn't have a handy source for marine ply and I was a bit more biased against plywood then than I am now. Building it today, I would not think twice about using plywood. But, if I wasn't using plywood, I would plank it longitudinally as much as possible. That would be challenging for the bow sections. At the very least some diagonal to the plank as apposed to a straight cross-plank. I still toy adding with midspan stringers on the bottom. At any rate, the bottom planks are 1 3/8" x 0.5" minimum. They are epoxied to the keel, chine logs and each other. They are also edge nailed with 3 1/3" long, 16d galvanized finish nails. A nailing technique that I use now places nails in close proximity to the previous so that I create semi-continuous "bands" of nails. See diagram below. Is it better than fully staggered nails? Maybe, maybe not. I forget now whether I ran 2 or three bands in the bottom over their 2.5' spans. Probably two. The 3.5" nails would go fully through two planks and partially into a third. Especially when driven below flush with a punch.

    Regarding the wide keel, with the cross-planked bottom: I like having the extra land for the bottom planks. Also the triangular chine log gave this extra land to the other end of the plank. To me, I visualize more of a cantilever support for the bottom plank with the extra lands on the end for support. Similar to a keel stepped mast vs. a deck stepped mast. The addition of the spray/lift rails really captures the out board end of these planks and a keel runner provides a modicum of acpture inboard, so I feel that I am adequate with the cross-plank as it is. I'm not rationalizing here am I? :eek: I just would not do it this way again.

    StripNailing.jpg

    I'm going to wrap this session up shortly, but I'll cover one more detail of the bottom. In Edwin's design, the chine in plan view is a continuous curve. Pointy bow, max width 6' forward of stern and narrowing again towards the stern. I was looking at this after planking my hull with it's constant deadrise and was not feeling content with the shape. The cambered chine(laterally) was bothering me. I wanted to have stright rins in all directions on the after half of the hull. It was begging for lift rails to correct this short coming. The problem was the stern is very narrow; 52": 8" narrower than max beam. Starting at midship, I added a .75"x2"(ish) strip, on the flat at the chine and ran it back to the transom. A second strip, .75"x1"(ish) was stacked, also on the flat over the first, going from the transom for half the distance of the first. I was able to increase the width of the stern by 3" at the chine, at the transom. Conversely, I feel that I may have added chine trippers to the hull by doing this. Because of this, I'm not real eager to try to push the hull to it's design speed limits. Using the new width as a starting point, I would run lift rails straight forward until I needed to curve them in to match the forward hull sections. I build lift rails by cutting a 16' SYP 2x4 on the diagonal, corner-to-corner. Heavy! :eek: But, holy cow strong. The forward sections were ripped, vertically in thirds to accomodate the bow curvature and the very forward sections were build as a separate piece with mahogany as I thought they were going to be finished bright. They were subsequently covered with paint. Regardless, the mahogany was easier to work than the SWP. Were I to start again, I would do away with the inward curvature of the hull in it's after sections and would not even put a chine log on the inside of the hull. I would utilize the lift rail in a dual capacity as an external chine log/lift rail. Without the inward curvature, a straight run would commence at the chine and my chine-trippers would be non-existent.

    Maybe, you can start to see how I was concerned about the weight of the hull. I felt the lift rails were a positive regardless of the weight. More to come. Gotta give it a break.
     
  6. PAR
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    PAR Yacht Designer/Builder

    No problem with copyright on those design Greg. It was designed in the late 1920's (I think), so you're pretty safe.
     
  7. LP
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    LP Flying Boatman

    With the completion of the lower hull, it was flipped and attention could be given to fitting out the topsides. Framing for the forward and side decks was added and I was noticing that height of the sheer was very low. It was as designed by Monk, but noticably low. I started looking at possible resolutions to another short coming in my short-sighted initiation of a boat build.

    I had planned to use 1x6 mahogany for coamings and so I used this as a basis for any further deviation from the basic design plan. I could set the bottom of the coamings levelish to the bottom of the side deck structure and any addition height would be determined by the height of the coaming. As it worked out, I could raise the sheer by 2.25" and still have the coaming standproud by an inch. I was able to add three layers of .75"x.75" strips at the sheer to accomodate this change. The old deck beams were cut off and new ones were laminated and installed. I was concerned about building up the side decks at the transom because they would have pretty much tapered to zero width. Instead, I chose to taper them down to the design deck height to maintain the side deck width. In retrospect, I think I should have built the side decks up all of the way to the transom. This would have lead to a "barrel-back" appearance and I think that would have been completely acceptable. As it is now, I have a straight sheerline, except for the last two or so. I've had trouble with this appearance from the beginning, but accepted that it was there and moved on. With the installation on the coamings, I allowed them to initially follow the side deck proflie, but then brought them back up with a fin type profile to try to draw visually away from the drooping stern decks. I think that has worked relatively well this way, though fins might be more of 50's look rather than the styling of the original design.

    It was about this time that I gave the boat it's "pet" name: Hacked. :rolleyes: I had hacked the design by Ed Monk. I had gotten to the point where I felt I was hacking the boat together. Plus, there was a small reference to Hackercraft in the name and styling of the boat.

    Later.:)
     
  8. PAR
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    PAR Yacht Designer/Builder

    HBWB (Hacked By Wood Butcher) . . .
     
  9. LP
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    LP Flying Boatman

    Sorry no witty pun to respond with. :p
     
  10. PAR
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    PAR Yacht Designer/Builder

    Name it after your mother in law or wife and build up spontaneous nookie credits, for next to nothing. It sure beats an equivalent amount, of taking out trash on trash night for a few months, to accrue the same number off spontaneous nookie credits. Think man, think, this is important stuff . . .
     
  11. LP
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    LP Flying Boatman

    Paul, you're confusing me with someone that needs spontaneous nookie credits. :p:p:p Spontaneous boatbuilding credits. Now that is something to get excited about. :D:D:D Letting the wife drive the boat on it's first outing. Now we're talking both kinds of credits. :idea::idea::idea:
     
  12. LP
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    LP Flying Boatman

    Here is the Freeship file I created to replicate my build. It doesn't have the full 6 inches of mystery length. I think that the extra length came from a lenthened stem profile and maybe from transom shift. I recall fiddling with the stem location a bit before locking it in.
     

    Attached Files:

  13. LP
    Joined: Jul 2005
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    LP Flying Boatman

    Tach check

    Well, I just did a tach calibration test with a timing light tachometer. It appears that my tach is calibrated correctly. That means that I am WAY under propped. :eek: It's bad that I engine so hard, but I was really hoping the indication was correct. This means that I can really increase the pitch of the prop. I need to decrease RPM by 1000-1700 RPM. Online tech information suggests a 2" change in pitch to get a 300-400 RPM change. This would mean a pitch change of between 5 and 8 inches. Fortunately, I have a shop that has a large selection used props. I think they will work with me to get the pitch right. I've cleaned up the 12" prop that came with the engine and put it on, but I suspect 15" will be a more appropriate pitch to work from.
     
  14. LP
    Joined: Jul 2005
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    LP Flying Boatman

    Took the boat out last night with a higher pitched prop and some engine "tuning." I adjusted the idle mixture to what I though was a more optimum setting. Not! It was mid-fifties outside and a little damp. All I succeeded and was making the engine bog down at low power. Fiddling with the choke and nursing it up, I was able to get it to it's top end power output. My first time out, I was getting indications of 6500 RPM. This time out, I was maxing out at 5800 RPM and getting less speed. 25 MPH ish. I thought I had confirmed my tach calibration, but I'm beginning to doubt it again. When turning the indicated 6500 RPM, the engine sounded strong and it didn't sound like it was over revving. At the 5800 RPM, it sounded like it was loading up and working too hard. I took the pitch from 11" to 13" on the prop. I may go back to the 11" for furthur tests, especially during engine tuning as it takes me back to known reference.

    I was also getting an indication of 16 volts on the electrical system. I'm not familiar with how stators function. Generator v. alternator tendencies. I suspect it is a generator by function. At 5000 RPM indicated, I was seeing 16 volts and at 3000 RPM indicated, it was showing 14 volts. I'm not sure what I should be seeing as far as voltage indications with this type of electrical system. Can anyone say id 16 v is too high. I used the starter a lot. I would think that a low battery would pull the voltage down so that wouldn't be the source. Is there a voltage regulator in this type if system?

    Between the carb adjustment, prop change, the voltage indications and the cooler weather, I kept the run short to avoid damaging anything. If the weather was warmer, I most likely would have dane a proper carb adjustment with the boat in the water.
     

  15. Yellowjacket
    Joined: May 2009
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    Yellowjacket Senior Member

    If you were turning 6500 before and you wanted to bring it down to 6,000, you needed only about 9% more pitch. You added almost 20%, so yes, it's going to be over propped and it's going to bog, that's too much pitch.

    For your present setup you needed something closer to a 12 inch pitch, 13 was too much.

    Your tach is probably right. Your best pitch is somewhere between overspeeding the motor and overloading it. If you are messing with the choke to get to full power you are probably running too lean and that might mean you aren't making as much power.

    Also check your setup. Try raising the motor angle to get more boat out of the water, or raising the motor higher on the transom with some shims (paint sticks work well) under the motor saddle. If you can reduce the drag the motor will pull more rpm's and power and you will go faster. Before you throw away the 13 you need to optimize the setup and see if you can pull it. You are at 5800 rpm, but there's probably a lot more slip in that higher pitch prop at that lower speed that would go away if you went faster. You want to run that motor at 6,000, not any lower than that.

    Also could be that your 13 inch prop is a dog and the 11 inch was a much better prop. I'd try to work the jetting first and the the setup, and then if you can't get it to 6,000 with optimizing the setup and motor tuning then I'd go back to a 12 inch pitch.

    16 volts is too high unless you are charging at a high rate, but after it gets charged it should come down to more like 14.5 If it stays that high and you aren't charging fast it's gonna boil out the acid in the battery.

    Racers have a saying... "Don't change two things at once". If you do you don't know for sure what the effect of the changes were. You violated that rule and unfortunately you don't know for sure what caused the lower speed and lower rpm. Change the carb back and make sure you have the right power and then change one thing at a time.
     
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