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AK Angler



Joined: 18 Nov 2003
Posts: 327
City/Region: South Central
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Rod Holder
Photos: Rod Holder
PostPosted: Sun Dec 14, 2014 12:58 am    Post subject: Reply with quote

Sunbeam - You're spot on with your description of the green epoxy being like hard cheese. And - in my opinion - I'd say that there is at least some benefit to drilling holes for through-bolts while the epoxy is still green. There is (as you mentioned) significantly less dust created by the drill, and it does make the drilling fast and easy, so I am able to move on to the next step in the installation sooner. Plus, there's less chance of the drill bit 'wandering' like it might on the hard surface of cured epoxy. Still, since green epoxy has very little strength, you don't want to fully tighten the bolts, or apply any significant load, before it fully cures.

Also, if your fastener of choice happens to be a screw instead of a bolt (like may be needed in a blind hole), you can drill a pilot hole the same size as the 'core' of the screw (the shank?), and the threads will easily embed into the green epoxy. So, it's kind of like molding threads, instead of having to force the screw to cut threads, which can be problematic in a thick plug of fully cured (and very hard) epoxy.

Anyway, it's certainly not necessary, and may not be appropriate for all situations, but finishing the machining operations while the epoxy is still green has its place.

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Sunbeam



Joined: 23 Feb 2012
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City/Region: Out 'n' About
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C-Dory Year: 2002
C-Dory Model: 22 Cruiser
Photos: Sunbeam
PostPosted: Sun Dec 14, 2014 3:08 am    Post subject: Reply with quote

AK Angler wrote:
Also, if your fastener of choice happens to be a screw instead of a bolt (like may be needed in a blind hole), you can drill a pilot hole the same size as the 'core' of the screw (the shank?), and the threads will easily embed into the green epoxy.


I'll have to give that a whirl. I've typically either set waxed (tapered) screws into wet epoxy, or tapped or drilled cured epoxy (the latter two most often). But I can see a place for the "cheese cutting" way with a tapered screw - going to keep that in mind. Always something new to learn Thumbs Up
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AstoriaDave



Joined: 31 Oct 2005
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City/Region: Astoria
State or Province: OR
PostPosted: Sun Dec 14, 2014 11:50 am    Post subject: Reply with quote

I have used this trick numerous times on epoxy which is very slightly green, aka not fully cured, but also not tacky to the touch, for drilling and tapping. If you try it on really green epoxy, it really fouls the drill, and tapping finer threads is hopeless.

Takes careful timing, but works great!

Another tip. If the epoxy plug is thick enough, a bottoming tap run into a pilot hole which does not penetrate the plug will give you a hole that will not leak through, ever. Shorter bolt, and the usual sealant or bedding still required, to prevent frost wedging.

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Blueback



Joined: 02 Oct 2004
Posts: 235
City/Region: Qualicum Beach, Vancouver Island
State or Province: BC
C-Dory Year: 1990
C-Dory Model: 16 Angler
Vessel Name: Blueback
Photos: Blueback
PostPosted: Sun Dec 14, 2014 3:59 pm    Post subject: Reply with quote

thataway wrote:
As Dave, I would surely recommend that all of the penetrations in the deck be epoxy sealed by routing out the core, and filling with epoxy. (Also particularly true of windlass, where there is compressive load put on deck core).

If you are using the Butyl tape, I would be sure that the bolts are checked for tightness regularly ( I use some blue loctite on the threads), because the tape seal depends on keeping pressure. Be sure that the area around the hole in the deck which the rode passes thru, also has a good seal with the butyl tape. This means that the deck should be flat and fair (non skid removed--either ground off, and faired, or filled with thick epoxy, and faired)

I have also used Boat Life Life Seal. Life Caulk works, but has a longer drying time (Polysulfide). Either are more tolerant of irregularities in the deck surface than the butyl tape.

Thataway-- you are a perfectionist in your methods and instructions for all penetration into the transom or deck fittings and oversize drilling-routing out the core, filling with epoxy and then drilling to the appropriate size etc. is unquestionably the best method. However, how many have had dealer installed motors and many deck accessories installed in their get it done at a cost the consumer is prepared to pay methods (1-step)? That is drill caulk and bolt using of course the best available caulking compounds available. And, having said that - how many within the the warrant period have found a problem with this method? Further, I installed an outboard on my C-Dory using the dealer method in 1990. Then last year I pulled that motor and had the dealer install a new (to me) 50HP Honda and - you guessed it -they just drilled, caulked and bolted it on without the many hours for a 2 step process which at a $100/ hour I am not willing to pay. Further, the original motor's bolt holes showed no signs of water penetration.
So I wonder if the science and development of marine caulking compounds, applied in the right manner, have not changed the necessity of the old 2-step methods. Further, I wonder if we aren't going beyond the current dealer and factory 1-step, to a 2 step method because we have the time and it makes us feel good? Just asking??

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Sunbeam



Joined: 23 Feb 2012
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C-Dory Model: 22 Cruiser
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PostPosted: Sun Dec 14, 2014 4:14 pm    Post subject: Reply with quote

Blueback wrote:

So I wonder if the science and development of marine caulking compounds, applied in the right manner, have not changed the necessity of the old 2-step methods. Further, I wonder if we aren't going beyond the current dealer and factory 1-step, to a 2 step method because we have the time and it makes us feel good? Just asking??


Blueback,

You addressed Thataway, but I hope you don't mind an additional response -- my opinion and experience.

First of all, you are correct. The vast majority of builders and dealers simply use a bedding compound to "seal" penetrations into core. Some shops - many semi-custom and custom - do close out the core with thickened epoxy, or by laying in solid glass to begin with. This takes more time, and so costs more. The general public is not necessarily aware of the need/advantages, and no-one really is looking to pay more for a boat, so this doesn't change quickly or with everyone.

I do think it is important. Likely that's because I've spent countless agonizing hours removing and replacing saturated deck core, almost exclusively caused by leaks that got past bedded fittings. I've also seen many otherwise great boats consigned to the "out back" area at yards where boats go to die. Often this was because leaks had caused deck core problems, and, if one is going to have a yard repair them, it can get very expensive (labor). Hence many older boats aren't "worth it" and they go out to pasture.

Having decided I was past my re-coring days (I sure hope, anyway), I made sure my C-Dory was 99% dry when I bought it (had been stored indoors). But I immediately set about eliminating that 1%, plus prophylactically closing out the core on other penetrations. I know myself, and I couldn't relax using my boat otherwise. Also, as annoying/time consuming as it is to do this, it's twenty times harder/more time-consuming/more expensive to correct problems than it is to deal with it before hand.

Now, does that mean every cored boat (including every C-dory) is about to become soaked? No, not at all. First of all, it takes time. Secondly, there is some luck involved. Some only-bedded hardware lasts longer than others. Thirdly, there is usage. If one's boat is stored indoors or under cover, and then one takes it out ten times a year for a week (or a month), it doesn't really get a chance to have a problem. No water (or water for a short time period) means no leaks and no damage. Also, the more/harder a boat is used makes a difference. Boats "work" and flex some when underway (or trailering), especially when in rougher conditions. This is going to be more likely to "loosen" a place that is only bedded, not closed out, and potentially cause a leak.

I don't believe that any advances in sealants or bedding compounds have overcome this problem (or necessarily could, given the givens). In fact, ironically, some of the "older" compounds are still very good, and some would argue that they are superior than newer ones. For example, polysulfide and butyl. (Also all compounds have strengths and weaknesses and are better or worse for specific situations.)

That's how I see it anyway. Luckily in the boating world it is still basically up to each boat owner to proceed as they see fit, and for the most part no-one else need agree.

Sunbeam
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Blueback



Joined: 02 Oct 2004
Posts: 235
City/Region: Qualicum Beach, Vancouver Island
State or Province: BC
C-Dory Year: 1990
C-Dory Model: 16 Angler
Vessel Name: Blueback
Photos: Blueback
PostPosted: Sun Dec 14, 2014 4:44 pm    Post subject: Reply with quote

Sunbeam wrote:
Blueback,

You addressed Thataway, but I hope you don't mind an additional response -- my opinion and experience.

First of all, you are correct. The vast majority of builders and dealers simply use a bedding compound to "seal" penetrations into core. Some shops - many semi-custom and custom - do close out the core with thickened epoxy, or by laying in solid glass to begin with. This takes more time, and so costs more. The general public is not necessarily aware of the need/advantages, and no-one really is looking to pay more for a boat, so this doesn't change quickly or with everyone.

I do think it is important. Likely that's because I've spent countless agonizing hours removing and replacing saturated deck core, almost exclusively caused by leaks that got past bedded fittings. I've also seen many otherwise great boats consigned to the "out back" area at yards where boats go to die. Often this was because leaks had caused deck core problems, and, if one is going to have a yard repair them, it can get very expensive (labor). Hence many older boats aren't "worth it" and they go out to pasture.

Having decided I was past my re-coring days (I sure hope, anyway), I made sure my C-Dory was 99% dry when I bought it (had been stored indoors). But I immediately set about eliminating that 1%, plus prophylactically closing out the core on other penetrations. I know myself, and I couldn't relax using my boat otherwise. Also, as annoying/time consuming as it is to do this, it's twenty times harder/more time-consuming/more expensive to correct problems than it is to deal with it before hand.

Now, does that mean every cored boat (including every C-dory) is about to become soaked? No, not at all. First of all, it takes time. Secondly, there is some luck involved. Some only-bedded hardware lasts longer than others. Thirdly, there is usage. If one's boat is stored indoors or under cover, and then one takes it out ten times a year for a week or a month, it doesn't really get a chance to have a problem. No water (or water for a short time period) means no leaks and no damage. Also, the more/harder a boat is used makes a difference. Boats "work" and flex some when underway (or trailering), especially when in rougher conditions. This is going to be more likely to "loosen" a place that is only bedded, not closed out, and potentially cause a leak.

That's how I see it anyway. Luckily in the boating world it is still basically up to each boat owner to proceed as they see fit, and for the most part no-one else need agree.

Sunbeam

Thank you for that Sunbeam and all you points are well taken. Possible your biggest reflection is -how long the boat is in the water and when its not in the water how it is stored. However, a chain is only as strong as its weakest link and in this case I refer to the method used to mount the motor. All those who have a dealer or factory mounted motor put you hands up. So while we are worrying about a deck mounting method the motor mount is the weak link if a dealer did it. Do I have an answer here no - its just an oxymoron that intrigues me.
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Sunbeam



Joined: 23 Feb 2012
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C-Dory Year: 2002
C-Dory Model: 22 Cruiser
Photos: Sunbeam
PostPosted: Mon Dec 15, 2014 1:40 pm    Post subject: Reply with quote

Just this summer I removed the engine from my transom (just used an engine hoist and moved it away from the transom by a few inches so I could work). I did it for a few reasons, but one of them was because those were the *last* holes in the transom that I had not gone in and closed out the core on.

As expected, there was just a small amount of sealant (even if I were just using sealant I would use much more than I have found on things I have removed - it was a bit skimpy) and then bare balsa core. The core was dry. However, my boat had 50 hours on it when I got it and had been stored indoors, so it was not much of a test. I did of course go ahead and close out the core on all four holes. Not only does it protect the core, but it creates a hard area to tighten fasteners on (soft core can "dimple" when torqued on, although large washers or transom plates can alleviate that).

Where I *did* find wet core, even with the "stored indoors and very few hours" was below the transom drain tube. That does not have a good flange/faying surface, and there was barely any sealant around it (so it could have been better, even with only sealant). At the point where I took it apart there was only around two square inches of damp core, so it was easily removed and would have been taken out anyway for my epoxying (I completely removed the core in this area and went to a garboard drain style plug, as shown in the Sunbeam ~ 22 Cruiser thread). I would not have wanted to see it years later if I had not done anything and had kept the boat in the water, but I can't say for sure what it would have looked like since that never happened. The engine bracket has a much larger faying surface than that brass tube did.

Again, you are correct in that our 99% of our engines are installed by just drilling through the core and using sealant. And obviously the boats don't instantly melt. I'd pay special attention to it if I were keeping a boat in a slip, even if I were not "anal" me. For me even though I store it indoors when not in use, I just wanted to be able to relax and not think about it if, say, I did The Great Loop and wanted the boat in the water for months on end.

Some of the boats (likely 2006 and newer) have foam cored transoms. The foam is likely more water resistant than balsa (although balsa is pretty good in that respect, really), but it is still in my opinion a bad idea to let water get in because there are nearly always small voids in the core-to-laminates bond area, and water in between them running around may have a part in de-bonding, and well, just better to keep any cored structure dry inside.

If you keep your boat indoors or covered, and don't use it for more than a few weeks at a time (this is likely typical for many), you can "get away with" a lot and likely never have any problem. After all, people make cardboard boats and race them -- they just don't keep them in the water for long (and obviously any C-Dory is miles better than cardboard; I wasn't implying any connection - just stating an extreme to illustrate).

My thoughts anyway,
Sunbeam
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Blueback



Joined: 02 Oct 2004
Posts: 235
City/Region: Qualicum Beach, Vancouver Island
State or Province: BC
C-Dory Year: 1990
C-Dory Model: 16 Angler
Vessel Name: Blueback
Photos: Blueback
PostPosted: Mon Dec 15, 2014 2:14 pm    Post subject: Reply with quote

Sunbeam wrote:
Just this summer I removed the engine from my transom (just used an engine hoist and moved it away from the transom by a few inches so I could work). I did it for a few reasons, but one of them was because those were the *last* holes in the transom that I had not gone in and closed out the core on.

As expected, there was just a small amount of sealant (even if I were just using sealant I would use much more than I have found on things I have removed - it was a bit skimpy) and then bare balsa core. The core was dry. However, my boat had 50 hours on it when I got it and had been stored indoors, so it was not much of a test. I did of course go ahead and close out the core on all four holes. Not only does it protect the core, but it creates a hard area to tighten fasteners on (soft core can "dimple" when torqued on, although large washers or transom plates can alleviate that).

Where I *did* find wet core, even with the "stored indoors and very few hours" was below the transom drain tube. That does not have a good flange/faying surface, and there was barely any sealant around it (so it could have been better, even with only sealant). At the point where I took it apart there was only around two square inches of damp core, so it was easily removed and would have been taken out anyway for my epoxying (I completely removed the core in this area and went to a garboard drain style plug, as shown in the Sunbeam ~ 22 Cruiser thread). I would not have wanted to see it years later if I had not done anything and had kept the boat in the water, but I can't say for sure what it would have looked like since that never happened. The engine bracket has a much larger faying surface than that brass tube did.

Again, you are correct in that our 99% of our engines are installed by just drilling through the core and using sealant. And obviously the boats don't instantly melt. I'd pay special attention to it if I were keeping a boat in a slip, even if I were not "anal" me. For me even though I store it indoors when not in use, I just wanted to be able to relax and not think about it if, say, I did The Great Loop and wanted the boat in the water for months on end.

Some of the boats (likely 2006 and newer) have foam cored transoms. The foam is likely more water resistant than balsa (although balsa is pretty good in that respect, really), but it is still in my opinion a bad idea to let water get in because there are nearly always small voids in the core-to-laminates bond area, and water in between them running around may have a part in de-bonding, and well, just better to keep any cored structure dry inside.

If you keep your boat indoors or covered, and don't use it for more than a few weeks at a time (this is likely typical for many), you can "get away with" a lot and likely never have any problem. After all, people make cardboard boats and race them -- they just don't keep them in the water for long (and obviously any C-Dory is miles better than cardboard; I wasn't implying any connection - just stating an extreme to illustrate).

My thoughts anyway,
Sunbeam

Hey Sunbeam your a great logical corespondent --
I am going to close this off by saying this-- there are a good, better, best, method- IMO:
Good - drill and caulk
better - drill, caulk liberally and store many ashore on a trailer
best-- your at home with love method - drill oversize - epoxy and re-drill - etc.
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