Need advice for a project

[kemo sabe]

Hello all - I am the proud owner of a 2320 that I will be launching in the spring (purchased late fall as a left over). One of the projects that I am trying to plan is the installation of a dorade box on the pilot house roof. I need to drill a 3 1/2 " hole for the main area where air will enter and then mount a 2 piece sleeve.
I saw some suggestions about how to drill the main hole starting from inside the house and then finishing from on top so that I get a nice clean edge on both topside and inside.

These 2 sleeves are then joined with 4 thin bolts with the roof in the middle of the sandwich. My concern is how to drill the 4 holes properly thru the roof so that the bolts will fit through the corresponding small holes on the edges of the sleeves........where there is very little room for error. The only idea that I have been able to think of is to start with a thinner drill but since the bolts will need to be only about 1/8th" in thickness, that won't buy me much of a margin for error.

Any tricks for drilling perfectly straight from above or below will be GREATLY appreciated.

sarge

 

[DaleH]

I would drill 1/8" hole through, starting from each side. Then open it up to 1/4" with a spade bit. Duct tape the bottom hole, wet-out the core with thin epoxy, then fill with slightly thickened epoxy. Then you can use the epoxy 'plug' as a guide where the bolt holes have to go through from each side.

But if you needed to fudge a bit to get the 2 bolt holes to meet, it will be done so with-inside the plug, so you don't compromise the roof wood core.

EVERY through hole (at least those through a wood core) on my boat is surrounded by such an epoxy plug.

 

[kemo sabe]

Hi Dale -

Thanks for taking the time to try to help me with this. I must confess that I can't yet picture your suggestion which, I am sure, is a good one. Will re read a few more times and work on understanding. I may take a few pics and send a pm to be sure that I haven't asked this ? incorrectly.

sarge

 

[Megabyte]

What you are doing is similar to the repair I did with my rocket launchers.
I did an epoxy repair and plug as Dale suggested.

Look here:
viewtopic.php?f=11&t=10258&p=72869&hilit=rocket+launcher+repair#p72869

 

[DaleH]

And here's one with pictures (1/2-way down) showing epoxy plugs used for the install of pop-up cleats.

viewtopic.php?f=11&t=1962

 

[HOTPURSUIT]

I installed a plastimo dorado box on my 2520. Have you already purchased yours? reason I ask is are you sure there are long thru bolts. Mine attached with 3/4" long screws to attach the top piece and 3/4" long screws to attach the bottom sleeve. Mike

 

[DaleH]

I installed a plastimo dorado box on my 2520. Have you already purchased yours? reason I ask is are you sure there are long thru bolts. Mine attached with 3/4" long screws to attach the top piece and 3/4" long screws to attach the bottom sleeve.

I did mine similar to Mike. I glued the bottom vent piece in place, which formed the tube. On my dorade box, the cover (with baffles) is simply held on by 4 screws, also set into blind-hold epoxy plugs. I never put a screw or bolt into or thru wood without such a plug.

 

[kemo sabe]

I installed a plastimo dorado box on my 2520. Have you already purchased yours? reason I ask is are you sure there are long thru bolts. Mine attached with 3/4" long screws to attach the top piece and 3/4" long screws to attach the bottom sleeve. Mike

Hi Mike - I have purchased the box and I decided to get the longer version, like Dale's. In the longer version, the 2 piece vent sleeve happens to have 4 mounting holes on each part and, since they line up with each other, I assumed that they need to be bolted together with the roof in the middle. The larger Dorade box looks like it just sits on the roof with the far end (which is closed) perched over the vent........so the air has a little farther to travel before it gets to the vent opening. The big Dorade scoop also screws off and can be replaced with a screw on cap.

The more I think about it, all the vent sleeves do is provide an air passage and have no weight or tension to bear, so maybe I purposely do not align the 4 mounting holes from above and below and simply use screws to hold them in place. If I understand the plug concept, I want to make the pilot holes for various screws oversize and then epoxy fill and then re drill correct, smaller pilot holes and use stainless screws.

I am not sure if Dale is also recommending doing something similar with the large 3 1/2 inch hole or if I can just fill the sides of the big hole with 5200 as I slide the first 1/2 of the sleeve in place. I can see that making a plug for all screws will provide a better anchor for the screws and place much less stress on the roof itself BUT I am not sure how that would work for the 4 screws needed from BELOW to anchor the first sleeve section. Unless I really thicken the epoxy it will just want to run out of any plug I try to make from below,

I apologize for being so numb about this and Really appreciate the help !
sarge

 

[kemo sabe]

I would drill 1/8" hole through, starting from each side. Then open it up to 1/4" with a spade bit. Duct tape the bottom hole, wet-out the core with thin epoxy, then fill with slightly thickened epoxy. Then you can use the epoxy 'plug' as a guide where the bolt holes have to go through from each side.

But if you needed to fudge a bit to get the 2 bolt holes to meet, it will be done so with-inside the plug, so you don't compromise the roof wood core.

EVERY through hole (at least those through a wood core) on my boat is surrounded by such an epoxy plug.

Hi Dale - When you have a minute, please read my response to Mike below and let me know if I am getting this and where I need to adjust my thinking.
Sorry to be the numbest proud owner on the site !
sarge

 

[DaleH]

The more I think about it, all the vent sleeves do is provide an air passage and have no weight or tension to bear, so maybe I purposely do not align the 4 mounting holes from above and below and simply use screws to hold them in place. If I understand the plug concept, I want to make the pilot holes for various screws oversize and then epoxy fill and then re drill correct, smaller pilot holes and use stainless screws.

Yup, drill four 1/4" holes from top, 3/4" deep (put tape on bit),

-Fill with epoxy (buy the ~$20 sample kit from Larry @ www.raka.com - or see me when it's warmer, as I have almost a gallon on hand ) and let it cure.

-Then drill 5/8" deep hole at least the diameter of the BODY of the SS screw you will use, likely a #8

-When cured, insert screw w/ silicone or BoatLife LifeSeal

-and be done with it

I would probably just tap-drilled body size drill from below and goop-up and screw in. Make sure bottom holes are NOT directly under the top screw holes, stagger them.

Do same for box via the 'top' screw method.

 

[kemo sabe]

The more I think about it, all the vent sleeves do is provide an air passage and have no weight or tension to bear, so maybe I purposely do not align the 4 mounting holes from above and below and simply use screws to hold them in place. If I understand the plug concept, I want to make the pilot holes for various screws oversize and then epoxy fill and then re drill correct, smaller pilot holes and use stainless screws.

Yup, drill four 1/4" holes from top, 3/4" deep (put tape on bit),

-Fill with epoxy (buy the ~$20 sample kit from Larry @ http://www.raka.com - or see me when it's warmer, as I have almost a gallon on hand ) and let it cure.

-Then drill 5/8" deep hole at least the diameter of the BODY of the SS screw you will use, likely a #8

-When cured, insert screw w/ silicone or BoatLife LifeSeal

-and be done with it

I would probably just tap-drilled body size drill from below and goop-up and screw in. Make sure bottom holes are NOT directly under the top screw holes, stagger them.

Do same for box via the 'top' screw method.

Thanks Dale !!!