After my post last night, I started looking at the propeller guard, with the purpose of figuring out how best to make it. Well, one thing led to another and I ended up staying up all night, finishing at 0600. It took me approximately 7 hours to complete, start to finish, including screen dump time to document the process. So, here is what I did…
First, in addition to the plans that I mentioned in my last post, I also had a couple of good photographs, including the one shown below.
To begin I opened my “Batfish-Part10-Hull10” part and saved it as “Batfish-Part24-PropGuards”. I then imported the “Docking Plans” I have into AutoCad, aligned it with the reference datum and scaled it to size. Next, I traced the outline of the guard using a polyline…
…That I filleted the corners of.
After this I added lines for the lateral bars and extruded a circle with a diameter of 0.5’ (6 inches). This is twice (or almost twice) what it appears to be in the photographs, but 0.5’ converts to 0.042”, which is about as small as I think I can make it and have it be both printable and strong enough to handle for construction.
Next, I imported and scaled another section of the plan sheet showing the guard facing forward and traced the bracket with a lines. I then copied these (red) lines to 2 of the 3 (green) lines that I previously drew for the lateral brackets.
These copied lines were then rotated 90 degrees about the z-axis…
…Then again about the y-axis, as may be seen below, in an image that has been rotated with the plans layer turned off.
Once again 0.5” diameter circles were extruded to make the lateral supports.
At this point I copied everything from the plan drawing to the profile drawing at the correct height.
Rotating the image allows better visualization of what is going on, as you can see below.
With the guard positioned correctly vertically and horizontally, I next copied it to the hull.
Next I copied the hull part out of the way, once again using the reference datum for proper positioning.
This allowed me to subtract the hull from the guard so that I would know where the lateral supports intersected the hull.
Knowing this allowed me to start the next step, making the flanges connecting the supports to the hull. In the image below, you can see the process I used to make these flanges. I first drew a circle at the end of the support, copied it once laterally and twice longitudinally.
The initial circle was then deleted and the two circles copied longitudinally and joined to form a somewhat elliptical polyline that was lofted with the circle to form the flange.
This flange was then copied easily to the end of the other perpendicular support…
…Copied and rotated to the ends of the other supports, and everything was joined together.
At this point I once again copied the hull into position…
…And subtracted it from the guard.
The angle supports were added next.
…Followed by guidelines for the cleat seen in the photograph of the guard.
The cleat was made using ellipses lofted along an elliptical arc. One was made then mirrored to make the other one.
At this point I turned my attention to mounting it to the hull. Although I might change it later, for the time being I used extruded circles from 4 of the 8 supports to make male pins to stick into the hull.
With the pins added, I mirrored the guard to the other side.
Then I copied the guards off to the side and subtracted them from the hull, leaving the female holes for the guards to mate with.
With everything completed, I moved the copied guards back into position and took some screen captures of the resulting guard and stern section.
As I said earlier, the guard supports are about twice the diameter they “should” be to provide extra support, but the effect, in my opinion, is not overwhelming and the guards look good.