70" CRC Outerlimits Electric Build

[fweasel]

That mount is really nice looking!

[WheelMan]

Been working on this build, trying to make some progress.

Transom plate is almost complete. Still needs a couple holes yet (water cooling inlets & steering link hole).

I'm learning the real challenge in this build is getting a stuffing tube made. Getting the proper amount of bend in the tube, so it lines up with both the strut and the coupler on the motor, is proving quite tricky, and time consuming. Not to mention ss tube is hard to bend, haha. This is no surprise to you guys I'm sure, but this is my first time doing this, so I'm learning.

My first attempt (pictured below) has too sharp of a bend in it I believe, as the flex shaft does not spin as freely as I'm sure it needs to, when I install it in the tube and spin it by hand.

However, I've grabbed some fresh tubing, and will attempt again (and again if necessary) until I get it right.

IMG_20190924_223703.jpg

[Mike W]

Looking good! My technique is to install the flex cable into the collet, allow it to take its natural curve, then trace that on a piece of cardstock and use it for a tube bend template.

[fweasel]

Everyone has their preferred method for bending a stuffing tube. I prefer to anneal mine. Heat the area that needs to be bent so it just starts to glow, then immediately quench it in water. I agree with Mike, I like to put something in the tube while bending. An annealed brass tube will bend quite easily with finger pressure. Once you have the shape you want, heat it up again and then allow to air cool and it will hold its shape. polish it up with some steel wool or fine grit sand paper to get rid of the carbon char and tarnish.

[Peter A]

Everyone has their preferred method for bending a stuffing tube. I prefer to anneal mine. Heat the area that needs to be bent so it just starts to glow, then immediately quench it in water. I agree with Mike, I like to put something in the tube while bending. An annealed brass tube will bend quite easily with finger pressure. Once you have the shape you want, heat it up again and then allow to air cool and it will hold its shape. polish it up with some steel wool or fine grit sand paper to get rid of the carbon char and tarnish.

Doing that to S/S will harden it. Brass tube absolutely.

[WheelMan]

Made some more progress this weekend.

Got the stuffing tube right, once and for all. Ended up needing to adjust the strut down a little, to get it pointing straight back, 90 deg to the transom (is that what it should be? Someone please help me here if that should be different?). Adjusting that down called for less bend in the stuffing tube, so that helped. Also, I just put a more gradual and larger radius bend in it, which made for far less drag on the flex shaft when installed. I'm happy with the final result. And I cut it a little shorter to leave about an inch of flex shaft showing between the end of the stuffing tube and the coupler on the motor. Seems to be about right based on what I've seen in pictures of so many other builds, so I hope I got that right.

Steering servo is mounted. Steering link is fabricated (aluminum rod with stainless rod ends). Boot installed in the transom to seal water out. Steering is pretty well set up.

ESC is mounted. Need to do some solder work, make leads to the motor and for lipo connection.

Getting close to epoxy time for the center rails and transom plate here once I get the final holes in everything.

Battery mounting is after that.

IMG_20190929_214859.jpg IMG_20190929_214918.jpg IMG_20190929_215211.jpg

[fweasel]

The strut position, height from the keel, looks a little too low to me. Usually the center point of the stuffing tube as it exits the transom is a little higher. As far as angle, you can start with the stinger set parallel to the keel and adjust as necessary after the maiden depending on how the boat runs.

[WheelMan]

The strut position, height from the keel, looks a little too low to me. Usually the center point of the stuffing tube as it exits the transom is a little higher. As far as angle, you can start with the stinger set parallel to the keel and adjust as necessary after the maiden depending on how the boat runs.

Well shoot, how much am I too low by on the strut, roughly? How will this change the boat's abilities, the way I have it?

I do have the strut set parallel to the bottom of the hull though.

[fweasel]

Hopefully someone with more v-bottom build experience will chime in with a more detailed height measurement for you. I've based my past build off a survey of other boats. I've also corrected boats that were setup with the strut too close to the keel. It can put the prop too low in the water if the boat is heavy, like yours. On smaller, lighter boats, where the prop can still get up to where it likes to run, it forces the hull to far out of the water, causing instability and chinewalk.

The best I can find are some rough photos of my friends 70" CRC build showing the approximate position of his stuffing tube from the keel.

IMG950413 (Medium).jpg IMG950440 (Medium).jpg

[WheelMan]

Thanks for the help man, much appreciated. Seems I've made for a lot of rework if I am going to move it. I thought I had done my research on this, but I guess I should have posted in here and asked before popping holes.

Did your friend have a build thread for that 70" CRC build of his? If so, I'd love to check it out.

[fweasel]

He doesn't post on the forums, but I did put up a few other pictures as well as a video of it running here: https://forums.offshoreelectrics.com...ain&highlight=

Let me know if there are other pictures you need and I can get them.

[WheelMan]

oh yeah, doh! That is the one you linked me to earlier in this thread. Sorry about that.

Thanks again for the info.

[WheelMan]

Just sharing some photos. Not a ton of progress has been made, but a little. Motor & Battery leads soldered up. Water inlets & outlets installed. Need to make a stuffing tube support, and make a few more final tweaks to the main cf rails.

Almost ready to start epoxying things in, and get started on the lipo mounting. Have some MBP adjustable lipo sleds I plan to use.

Once fabrication is done, and I have the maiden voyage in, it will be time for paint

IMG_20191008_172620.jpg IMG_20191008_173013.jpg IMG_20191008_171828.jpg IMG_20191008_172759.jpg IMG_20191008_173303.jpg

[fweasel]

I would suggest you raise your trim tabs up higher on the transom so that the leading edge is not flush with the bottom of the hull. Most recommend about a 1/16" to reduce drag. You might be able to just slot the mounting holes in the hull and fill the gap later with epoxy prior to body work and paint. The rest of the layout looks so clean, it makes me want to push my outerlimits build up onto the workbench.

[WheelMan]

Thanks for the suggestion man. I did not realize flush was not the goal.

I appreciate all the insight you've given me here on this build.

I really have very little clue what to expect out of this thing once I get it on the water. I'm sure I will learn what I've done right & wrong. But that's part of the fun!