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Electronics box fabrication questions

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Old 12-03-2018, 02:27 PM
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Default Electronics box fabrication questions

Rehabbing an 2000 Seapro SV2300. Recently had a local fabricator install a fold down tower to replace a striker t-top. I had previously purchased a used tower from a THT member, but the cost on modification was close enough to a new build, so new happened.
To make a long story short, we cannibalized the control box off the old tower. Its a wood core one off unit that needed some TLC, and modifications for new electronics. Suffice to say I enjoy a challenge, so I will be building a new box instead of fixing the old one.
So today i fabbed up a plug out of 1/2 MDF. This is my first try on glass work, so here are my questions:

Can I use ready patch for the first coat of fairing on the plug, or will the heat from the poly resin heat up and crack it out? Planning to sand and run a coat of bondo prior to PVA primer.

Is a 3/8 round over bit enough for the 90 degree angles? I can step it up to 3/4 if need be, just hesitant with 1/2 stock for the plug.

What is is a good veil to apply to the plug for a first coat? Planning on chop mat and 1708 bi-axial fabric for the rest of the mold with polyester resin.

Im sure there will be more questions as the process continues. Any help would be greatly appreciated.

And a quick shout out to James Gartside at Dark Arc Marine. They kicked butt on the metal work and were happy to answer all of my questions throughout the build process. If anyone needs any metal work around the Savannah area I can vouch for the quality of the work and the excellent experience.

Thanks in advance.

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Old 12-03-2018, 04:26 PM
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Is ready patch like joint compound? Similar to plaster. As long as you’re not putting it on too thick, cracking shouldn’t be too bad. Even if it does crack, your part should still be good. For a one off mold, I usually just use melaminewith plactecene clay for filets an radius. You can use it to fill cracks too. Then a few coats of mold release and make your part. It doesn’t matter if the mold survives as long as your part is good. Sometimes it’s even better to plan a take apart mold.
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Old 12-03-2018, 04:32 PM
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MShugg thanks for the quick response. Im hoping to be able to use the mold at least twice. I still have the other tower and would like to put it back together and get it ready to sell. I was planning to lay the mold glass about a half inch thick so I dont break it when the time comes to separate the part from the mold. Is that going to be enough or should I plan on incorporating some roving into the mold cast?
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Old 12-03-2018, 05:57 PM
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Man I had a very detailed writeup on doing this exact thing on another site but I can't seem to find it now. I'll see if I can drag up some pics at least when I get a minute. If you have the time to dig through my Mako 231 rebuild thread I used the same basic process to make some fishboxes, except that the additional step would be that they then become the mold for the box.

I like using the lightweight spackling compound that goes on pink and dries white for rough fairing MDF. Dries fast, sands easily. I coated the plug with Duratec - IMHO not even worth messing around with anything else. Rounded corners with a 1/2" bit. Make sure you build a few degrees of draft into your plug.

I used tooling gel coat for the mold, backed up by a couple layers of .75 oz CSM to start, then layers of 1.5 oz CSM and 10 oz cloth. Since then I've found that 1.5 oz mat works just as well as a first layer unless you have a lot of small detail, and builds twice as fast. 1/2" of glass would be way overkill, unless you're talking production mold. For two uses I would think 1/4" is more than enough, I got away with about 3/16" and could have easily pulled another part. If you build it thick enough with just CSM it would be fine for a mold.
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Old 12-03-2018, 06:28 PM
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Here are some old pics, hopefully they upload ok from photosuckit. Sequence should give you the general idea, happy to answer any questions about the specifics.

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Old 12-03-2018, 08:04 PM
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Hell Yes. Thats the same concept I'm working with for the control station. Next up is the Electronics Box for the lower station. Your work looks excellent. I assume the the picture with the air hose is showing how you got the mold of the finished box? How many PSI were you running? I would assume a blow off gun would be the way to go there to limit the amount of pressure applied?
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Old 12-04-2018, 06:48 PM
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Originally Posted by S0uperP0wers View Post
I assume the the picture with the air hose is showing how you got the mold of the finished box? How many PSI were you running? I would assume a blow off gun would be the way to go there to limit the amount of pressure applied?
yep. drill a small hole in a part of the mold you will either cut out, cover, or can easily refinish on the part, then cover from the inside mold surface with a piece of packing tape to seal it while laying up the part. I honestly don't remember what pressure was, don't think I worried about it too much so probably the 120-ish straight from the line? Been a while, I might have reduced it to 40-60 psi but I can't imagine I would have gone lower than that. Regardless, I don't think you'd be able to pressurize it enough with a normal air supply to break the mold or part. I had to whack the mold a few times with a rubber mallet to get the part to release, but then it popped right out with a couple puffs of air.
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Old 12-05-2018, 10:46 PM
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So today was dry fit day. The plug was the right size, and everything was running smooth. Got out of the tower, lowered the box down to a buddy, and then it all went bad. While I was screwing around up top my buddy, we will call him Ben to protect the innocent, thought it would be wise to try a chin up on the t top section of the tower. To make a long story short, after getting back up and chucking my slightly over weight ass around up in the tower, we discovered that rocking the tower from bow to stern resulted in over an inch of deflection in the floor in front of the console.
So after asking my slightly less overweight friend to do a pull up on the stern most section of the t top section it was determined that the floor was not glassed to the stringers or bulk heads, or something major has gone askew.
Suffice to say priming the mold plug had to take a back seat. Ripped off the rub rail, and after a few hours of drilling out rivets (seriously, rivets?) and removing what I would estimate to be 30 screws (and most of my will to live) it was ascertained that by merely lifting the gunwale mounted stainless rail that the liner and hull could be seperated. While I did not keep count I am fairly certain no less than seven never before uttered curse words were created.
While I think the general consensus would be that this is extremely unfortunate, I am somehow finding some level of excitement in trying to tackle a new challenge. It seems as though the half planned salvation of an 18 year 2 piece constructed relic has taken a turn down the avenue of [email protected]#* it, now I am going to customize this boat the way I want it.
Rebuild thread coming. This ole girl is getting gutted to the stringers and getting bullet proofed. After we get the tower and console removed, the motor removed, and everything I can reach through a hatch or inspection plate disconnected, my 2310 headache is going to become a slightly over 47 foot problem. Next stop, liner removal, and with it a new batch of questions:

1: I need an epoxy paste with a slow cure time, and hopefully some temperature tolerance. While I am in the south now, even on the best of days it wont hit 70 degrees. Would a different resin be a better option? I do not plan on gelcoating anything. This ole girl is getting awlgrip.
2: Anybody out there ever rebuilt a seapro sv? I realize this is not a legacy hull, and short of a stubborn lunatic like myself most folks would cut bat and find a new ride. Any pointers that could be offered would be fantastic. I realize not everything on the internet is true (bonjour), but from my limited understanding of 2000s era sea pro assembly the liner was designed to float over the stringers. My deck is not soft in any of the areas of deflection, so wtf else could it be?

The adventure continues.
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Old 12-06-2018, 03:44 PM
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US Composites' slow curing epoxy will take 2-3 days to full cure when its sub-50 degrees out.
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Old 12-07-2018, 04:14 PM
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Thanks. That should work perfectly.
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Old 12-09-2018, 03:09 PM
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Default Tower control box continued


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Old 12-09-2018, 03:25 PM
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So despite the hull/liner issues, progress has been made. Decided to add some contours to the top of the box for flush mounting electronics, binacle, and helm. Lower section of box received some areas for speakers. After filling and sanding, followed by filling and more sanding, then some clay was added to ease the edges at all the connecting points. I guess 3rd grade art class is finally paying off.
Once the last set of filler has dried and the (hopefully) final sanding can take place. Then it will be time for pva application.
Going to have to make a mold for the lower and upper section separately, and tab the two pieces together after they have cured.
Todays questions:

Decided to use epoxy resin instead of polyester. What do I need to make a paste to adhere the two parts together once they have been popped out of the mold? Hopefully I can use the same materials to bond the deck to the stringers once the hull gets popped apart.
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Old 12-10-2018, 04:33 PM
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Youll want to use cabosil as your thickening agent. Epoxy is a great choice for your deck to stringer bond and any other structural repairs. I would stick with polyester or vinylester ester for the parts your building outside the boat. It wets out easier, is less costly and unlike epoxy it can be gelcoated. Edit: Dont want to start a gelcoat and epoxy debate as some have gelcoated over epoxy successfully its just not the norm.
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Old 12-10-2018, 05:51 PM
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Ok so had a stroke of dumbass. Clay I used was no good. Cracked all up. Got some plastilla clay today. Tried making a few radius fillets for around the speakers ang got my butt handed to me. Even with a heat gun I couldn’t get it perfect. Going to give it another shot tomorrow.

Todays questions:

Do I need to PVA primer the plug before or after the clay fillets are put in?

Dave, I appreciate the insight. I’m going to awlgrip the electronics box to match the console. My plan once the mold is made, is to glass directly to the parting wax, and fair out he part before painting. Will this work or do I need to spray the awl grip in the mold after the wax? Concerned the heat will cause a problem.

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Old 12-10-2018, 06:23 PM
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Normally gelcoat is sprayed or rolled over the mold release wax. Plug, Primer, PVA, wax, gelcoat and then glass. You cant substitute Awlgrip paint for gelcoat in this process. Once the gelcoat kicks start laying glass over it. You can put epoxy over gelcoat without issue just not the other way. If you are painting then that will be done last over a faired and primed part.
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Old 12-11-2018, 05:46 AM
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Originally Posted by S0uperP0wers View Post
Ok so had a stroke of dumbass. Clay I used was no good. Cracked all up. Got some plastilla clay today. Tried making a few radius fillets for around the speakers ang got my butt handed to me. Even with a heat gun I couldn’t get it perfect. Going to give it another shot tomorrow.

Todays questions:

Do I need to PVA primer the plug before or after the clay fillets are put in?

Dave, I appreciate the insight. I’m going to awlgrip the electronics box to match the console. My plan once the mold is made, is to glass directly to the parting wax, and fair out he part before painting. Will this work or do I need to spray the awl grip in the mold after the wax? Concerned the heat will cause a problem.



Warm the clay and press it into the corners. You can buy a filleting tool, but I use an old socket in an extension. I warm the socket with a propane torch and draw it through the clay. This works like cutting butter. Use a razor blade to scrape away the excess clay. Coat the mold with either PVA or mold release wax. Ether works fine. Then you’ll clean, fair and paint the part.

The heat generated when the resin kicks may deform the clay a bit, but you can repair it before molding your second part.



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Old 12-11-2018, 08:00 PM
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Thanks shugg. Wish I had read this before tackling it this afternoon.. I got it pretty smooth heating it up to about 100 degrees and running my finger through it like applying a caulk bead. I will clean it up tomorrow with a socket. Grey putty from hell about to get whooped... I hope.

also sent you a pm about the aqua sport rebuild.
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