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Thread: 55" Dumas Scarab

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  1. Engine selection... 
    Okay I received my engines today and thought I would take a picture of the engines I accumulated while searching for the "right" engine.

    The Picco 65 and the YS-YZ53 are my cousins engines, he also talked me into going with the YZ-4-strokes. The YZ53 is the older version and the YZ63S's that I purchased are the "newer updated" version.

    The updates include a remote mounted fuel regulator (mounted away from the heat for better fuel temps) I can also mount the regulator wherever I want in the boat (The regulator is the item mounted on the pushrod tubes) Also the new cylinder has no liner, transferring heat better. The YS-63S is better, more reliable under a wide range of conditions. It was these improvements that made me lean towards the 63S....knowing heat will be a problem or concern to deal with. I'll keep you updated when I do more.......the wife has me installing new kitchen countertops this weekend, so no "hobby" stuff for a bit.
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  2. back at it.... 
    Okay it's been a week or two since I last worked on the scarab. So it's time to get back at it...spring / summer is coming fast.

    I started making an engine mounting plate that I can mount both engines to, and then install that as one item into the boat with the engines mounted and ready to go. I used a piece of 3/16" aluminum plate 5" wide and cut out the notches for the engines to set into.

    I am now trying to decide the best way to install some stringers. Also I am trying to plan for the best way to bolt the engine plate to the stringers also. The two pictures attached are of the engines mounted on the plate, and the second is the assembled plate in the boat where it needs to go. (The engines are as far back as I can mount them, otherwise they will hit the dash when I install the interior) I did a quick check of the CG 28% of the hull length forward from the transom? (That's the figure I see in a book I have) It obviously is nose heavy right now, but I still need to add all my servos, rx, batteries, fuel tanks etc. I should beable to get it balanced pretty close. I took some weight and put towards the rear and it helped balance it pretty good.

    Also after I get the stringers in and the engine plate mounted how I need I will most likely trim off some of the extra weight on it. I might narrow it up 5" is plenty wide, and I will most likely drill some "lightening holes" to reduce the weight also.

    Any suggestions are welcome. Is the 28% figure for CG close? The hull is 54" end to end 28% of that is 15.12" forward of the transom.
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  3. more progress 
    Today I worked on getting the stringers fit and in the boat along with a good mounting system for the engine plate.

    The stringers I made out of 3/8" x 1 7/8" ply. You can see in the pictures I had to notch the front out so the engine plate would set at the correct height to line up with the outdrive input shafts. I then took the same material and made the horizontal mounting surface for the engine plate to bolt thru(on the inner side of the stringers) For added strength I also epoxied on a 1/4" x 1/4" spruce on the outside side of the stringer (directly under the engine plate) and lastly I epoxied a piece of 1/16" ply on top to span the 3 pieces which will give it plenty of strength, plus a nice level surface for the engine plate to bolt to. Under the horizontal piece I installed 3 blind nuts on each stringer. I just "tacked" the stringers in place with epoxy for now, I will fiberglass all this later on.

    You'll also notice I did trim off quite a bit of the width of the engine plate and also added a few "lightening holes" I didn't want to get too many and sacrifice strenght. But as it is now I can take the engine plate and grab each end and twist....it won't budge!

    Now I have to try and figure out how to squeeze in (2) shafts for the drives (2) 16oz fuel tanks, (2) sets of exhaust a radio box that will hold (6) servos!! (1 servo or steering each drive, 1 servo for up and down trim on each drive, 1 servo each for engine throttle) (1) RX (1) battery and a few misc. items. All of this also has to leave room to allow the interior to slip in and out also. I probably should have made the radar arch removeable, so I could lift the interior more straight up....but as it is I have to lift the back up slightly, the pull it straight back. But I did a quick check and SHOULD!! have room for the above listed items!haha

    P.S. If you are wondering about the green tape on the engines.....I didn't have anything to plug the glow hole, carb, and exhaust...this was the easiest thing at the moment.
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  4.  
    That is some fine work Paint-boy!
     

  5.  
    Join Date
    10-11-2005
    Location
    Akron Ohio USA
    Posts
    55
    Earth magnets could be used to hole the hatch down and you wouldn't need to try to find the alignment holes when you get the engines started .
     

  6. Internal finish 
    Join Date
    04-03-2007
    Location
    NSW Australia
    Posts
    41
    G'day Paint Boy from Down Under

    You may be able to help on this one - are you going to paint the interior of the hull?

    I have a wooden monohull, & I am trying to find what's best to re-coat the bilge area

    Talked to a couple of Ship Wrights today, & for nitro spills - the best seems to be a 2 pack Epoxy finish
    not poly urethane, or polyester

    Does this sound right to you?
    I have only wire-brushed the old finish with drill attachments to rough it up a lot

    International coatings look to be the best choice so far

    any thoughts??


     

  7.  
    bad_boy2085 Thanks for the suggestion on the hatch insert. I don't have too much trouble lining it up in front. Since I have to slide it under the radar arch and it's a snug fit side to side it actually slips right into the holes in the front. BUT the magnet idea might be a good solution for securing the back of the hatch for a latch. Thanks for the idea

    Muddy I am unsure of what I will be doing to the inside of my hull if anything. But Epoxy would work just fine for something like that. I would also believe that any paint or primer that is catalyzed would hold up to glow fuel? I say "belive" as for I have never tested the glow fuel directly on paint.
     

  8.  
    Join Date
    04-03-2007
    Location
    NSW Australia
    Posts
    41
    Thanks - I have spilled some racing fuel on my bench once - it is (or was) laquered timber
    It looks like what brake fluid would do to painted suface after 1 week
    but it only took minutes to do the damage (turned it to jelly)
    that's why I'm trying to ask all I can about the toughest paint out there -
    Cos I only want to do this ONCE
     

  9.  
    Muddy,

    No problem with asking questions that's what this board is all about. Lacquer paint is a soluable paint. It will do exactly what you described no matter how long it has been on a surface to dry.

    Epoxy or any other catalyzed (primer or paint with a hardner) will hold up to most products spilt on it. Any quality automotive 2 part urethane paint or primer "SHOULD" hold up to your needs. I would still do a test panel and put some glow fuel on it to check how it holds up.

    You mention break fluid, Break fluid is hard on a cars paint (base coat clear coat) it will "stain" the surface but shouldn't "jelly" it up as you say.

    Hope any of this information helps
     

  10. Paint 
    Join Date
    04-03-2007
    Location
    NSW Australia
    Posts
    41
    G'Day paintBoy,

    I have emailed International Coatings, and an Australian company (Norglass)

    I can call in and talk to both of them (their agents)
    To see what's the toughest (not prettiest) finish for the bilge area that can handle chemical attack from fuels such as nitro, diesel, etc.

    After I see them, I'll let all you International Boaties know what I found

    Do power-boaters paint the hull internals, or did I inherit something from the "too hard basket"???


    I hope this is going to be of help to someone out there!!

    Cheers
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  11. Paint 
    Join Date
    04-03-2007
    Location
    NSW Australia
    Posts
    41
    Hi All,

    Saw the Head Man of Norglass Paints today, (a nice bloke)

    The Epoxy 2 pack paint is good for Alkaline resistance (external hull finishes)
    Polyurethane 2 pack finish is good for acid resistance (Nitro, if left in an engine separates into water and acid - real bad for carb needles!)

    So, I'm going to use "Shipshape Primer Undercoat - commonly used as a primer-undercoat and as a topcoat in the bilge areas of boats (real ones) because of its satin gloss finish" quote from the product catalogue

    www.norglass.com.au

    Following this, I'll use the 2 pack Northane Gloss... have a look at their website

    International Coatings is more a company that supplies paints for Container Vessels and Super Tankers - not the type of crowd who's interested in selling 500ml packages!

    Hopefully this will be the strongest anti fuel spill finish I can use on the interior hull.


    Hope this helps answer anyones queries about what to do if you got a Nitro hull like mine!!

    Also, I got trade prices
     

  12.  
    Paint Boy you sure do a great job on things i envy your talent. I do have one question for you though. You say you tacked the engine rails in with epoxy for now and will fiberglass later. If you remember i also have a scarab from Dumas. I thought i remembered when building mine that they suggested using polyester resin and fiberglass cloth on that hull as that is what they used. They did mention something that if you had to use epoxy you could brush on a thin coat of catalyzed finishing resin first and allow it to dry then sand off the wax. Are you planning on using epoxy with the cloth to reinforce the rails or are you going to use polyester resin? I think most fiberglass repair kits you buy at Auto parts stores are Polyester resin. Juat a thought that i had. Been so many different changes to stuff over the years that it may not make any difference now. I don't know.
     

  13. fiberglassing 
    dhaxt Sorry I didn't make myself clear on the process I am using on the stringers.

    Correct I did "tack" the stringers in with a coulpe dabs of epoxy (not for strength but more so to line them up and make sure they fit correctly)

    Eventually when I get ready I will prepare "grind or sand" the hull next to the stringers and apply the polyester fiberglass resin along with the fiberglass cloth. I will cut strips of the cloth to lay in the each corner of each stringer and lay resin under and over the cloth (I will do 2 layers of cloth for strength)

    I've been compiling a majorly long list of items I need to finish this project...it's getting longer and longer by the day. Everything from the 1/4 scale servos, fuel tanks, batteries, stainless bolts/nuts, push rods, fuel lines etc. I'll have to hurry and pay the bill before the wife sees it! This project is costing more than I first guessed.....oh well it's a hobby money doesn't count right?!?
     

  14.  
    I've been compiling a majorly long list of items I need to finish this project...
    Amazing how the little things add up!
     

  15.  
    Join Date
    04-03-2007
    Location
    NSW Australia
    Posts
    41
    Paint boy
    I didn't mention - your Scarab has turned out way cool

    Hope it flies!!

    good luck
     

  16.  
    Join Date
    07-21-2004
    Location
    Pittsburgh, PA
    Posts
    2,361
    keepin it alive
     

  17.  
    thanks for the "bump" up. I have been really busy working on the project. Making the radio box and trying to fit in 4 1/4 scale and 2 normal servos with 2 battery packs is quite a task.....It just BARELY fits in there...but I think it will work. I ended up having to "modify" the radar arch......aka cutting it off at the deck line.....I wil insert pegs into the arch that will slide into tubes in the boat.....so I can firsr put the interior in and then put the arch in.

    The reason I haven't been updating lately is because of the problems I am having logging onto the forums. I can only log on here at work.
     

  18.  
    Quote Originally Posted by paint-boy
    4 1/4 scale and 2 normal
    Hey Bud, just currious as to why you'd need four of the quarter scale servos? Those drives only need one each.

    Ps, Can't wait to see the progress.
     

  19.  
    DD, I needed two extras to help get the final price of the boat up more!!haha

    No actually they are for the power trim on the outdrives (1 each) So I will have 1 1/4 scale for steering and 1 1/4 scale for trim per drive....and also 1 normal servo for each engine throttle.

    I debated on if the trim needed 1/4 scales or not....but decided with how they work....there is technically constant pushing on the trim mechanics of the drive....and I'm hoping the 1/4 scales will tolerate that better.

    I'll try and post pictures of the progress this weekend.
     

  20.  
    Quote Originally Posted by paint-boy
    No actually they are for the power trim on the outdrives
    No way? Actual power trim.... That would be awesome to control the ride like that while underway. There are a few guys that make power trim tabs but thats another story.
     

  21.  
    Join Date
    07-21-2004
    Location
    Pittsburgh, PA
    Posts
    2,361
    are they outdrive servos digital? I would think the holding power would ne needed.
     

  22. Radio Box 
    I said I would post some pics of my progress so far.

    I've been busy (mostly thinking and planning) on building the radio box to house all the components I need in there. Attached are a coulple pictues of the box I've made so far with all the servos set in place.

    The 2 1/4 scale servos that are upside down towards the rear of the boat are for steering each outdrive.

    The 2 1/4 scale servos laying on their sides in the front of the box are for the power trim on the outdrives.

    The 2 normal servos recessed in the bottom are for the throttles.

    Mounted next to the steering servos are my battery packs (one on each side)

    Also if you look close you can see my H.D. switch mounted on the side next to the trim servo, I drilled the switch to attach the rod thru....which exits out the front via. rubber seal.

    I plan to mount the receiver directly above the throttle servos, between the steering servos. (I still have to make a mounting tray for that) I also still need find a spot to mount my voltage indicator light bar, and a charging jack.

    I started making my control rods today and have the steering and trim hooked up working alright (still some tweaking and adjusting to make it work perfect) My other outdrive and engine are in North Carolina at my cousins, he is making the custom flywheels, and prop shafts.

    Lastly: How can I attach a short video clip (AVI format) I took 2 short clips to show the outdrive steering, and one of the power trim. If it is possible to add a video clip I woul sure like to.
    Attached Images
     

  23.  
    Join Date
    07-21-2004
    Location
    Pittsburgh, PA
    Posts
    2,361
    bump...
     

  24.  
    Hey Paint Boy what happened nothing from you in a long time. Like to see your progress on your project.
     

  25.  
    Join Date
    01-12-2007
    Location
    Lombard, IL
    Posts
    65
    Quote Originally Posted by dhaxt View Post
    Hey Paint Boy what happened nothing from you in a long time. Like to see your progress on your project.
    Yea, whats up?? I love to see your fine work, hope all is well
     

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