Flybridge Re-Core

[spartonboat1]

This is regarding my re-coring efforts of the Flying Bridge of my 1972 43' DCFB. I bought her in 1997, and only used the FB for a couple years. I knew the coring was going bad, but it can be amazing how difficult it is to secure tradesman; even the yards have a hard time finding good people.

This has been on-going for 6-7 weeks, with limited time to apply to the work. Today I am posting some pictures from this weekend, Apr 9, 2016.

 

[spartonboat1]

Pictures of the Rockwell F50 reciprocating unit for cutting into the surface fiberglas over the coring.

 

[spartonboat1]

Pictures of the shoring up I did to support the bridge, while am up there working. The posts are sitting on 2x6's and are holding up 2"x6"x7' overhead for good distribution of support.

 

[spartonboat1]

Pictures before I lifted up the cutout, which was 2' by the width of the bridge. If it looks ugly, spare me the flaming...

 

[spartonboat1]

Pictures of bad coring under the cutout section. Found wet wood, even though have been inside heated.

 

[spartonboat1]

About the only "good" wood left, in this area. However, there are solid sections, but not yet exposed.

 

[spartonboat1]

Quick note that I will try to use Coosa Bluewater 26. I will use 1/2", if it has the flex to fit the flybridge crown. Coosa HQ says 1/2" should flex and is a physical replacement for plywood, but should be lighter and waterproof. Otherwise, may need to go to 3/8".

I wonder what Hatt uses for coring these days?

 

[oscarvan]

Keep going until you find solid wood. As far as your comment re drying time, a friend is rebuilding a boat inside, heated. It's been in there for 5 years, he STILL found wet wood when he cut open the deck.

 

[bobk]

Use the same thickness core as the original. If it wont bend, cut some thin kerfs into it or install it in 2 or 3 inch strips.

Bobk

 

[spartonboat1]

Use the same thickness core as the original. If it wont bend, cut some thin kerfs into it or install it in 2 or 3 inch strips.

Bobk

Intention was to lay down two 1/2" boards, West Systemed to floor deck, then West Systemed sandwiched to form a 1" layer. Would that fit the "same thickness core", as in above? The West System the original top layer down, then beautified and painted.

 

[Top Hatt Craig]

First I'd like to congratulate you on your determination in taking on this emense job. I am humbled by your skill and resolve to get your boat right.

I would like to ask what are the expectations in performing exploratory surgery on deck coring? How is it dealt with if the wet coring extends under walls or other inaccessible areas?

New here, thanks for your thoughts.

 

[DLCameron2]

Great job so far! Your engineering prowess is on display the way you supported everything etc. Have you considered using foam to replace the balsacore? http://www.defender.com/product3.jsp?path=-1|10918|2259972|2259998|2260006&id=22184 Structural foam is never going to rot. You have a ton of skill, obviously. I am sure you can figure out how best to install it. Hope Scott is fine! If you are coming to Mackinac Island please PM me.

Don

 

[jim rosenthal]

Multiple layers of thinner core replacement that add up to the original thickness are a better solution, but take more time and effort and expense. Coosa board is a great material for this; I have had good luck with it. I'm sure I have some of the same problems, but I am not tackling it yet.

 

[bobk]

Intention was to lay down two 1/2" boards, West Systemed to floor deck, then West Systemed sandwiched to form a 1" layer. Would that fit the "same thickness core", as in above? The West System the original top layer down, then beautified and painted.

It would, but as Jim said, a structural foam core would be the best. Lighter weight, never rot even if it gets wet again.

BTW, did you determine the points of entry of the water? You need to correct or eliminate them.

Bobk

 

[oscarvan]

Reference the "never rot" aspect of foam...... I've read several articles explaining how water intrusion leads to osmosis. Slower for sure and less destructive maybe but not "rot free". Water will always be the enemy.

 

[SEVEN]

Please keep the photos flowing. Most of us have a soft spot somewhere on our boats. We can all learn from your findings and expertise.

 

[34Hatt]

It would, but as Jim said, a structural foam core would be the best. Lighter weight, never rot even if it gets wet again.

BTW, did you determine the points of entry of the water? You need to correct or eliminate them.

Bobk

Coosa is fairly light and never will rot ? It is great stuff but costly.

Another good product for that application is nida core.

 

[jim rosenthal]

Coosa may absorb water, but in such small quantities and over such a long time as not to matter to us. And, yes, repairing the point of entry is also critical. I suspect it is usually a hole drilled by someone- builder or owner or repairman. Unfortunately.

 

[34Hatt]

Coosa may absorb water, but in such small quantities and over such a long time as not to matter to us. And, yes, repairing the point of entry is also critical. I suspect it is usually a hole drilled by someone- builder or owner or repairman. Unfortunately.

WRONG!

Were did you get your info?
I have seen pieces some sitting outside in water and mud for years!
Plus company even says you don't have to seal it to be water tight maybe I should't believe them it was years ago when I spoke to them about it

 

[bobk]

Guys, we are mixing apples and oranges, perhaps other stuff too here.

Osmosis as used relative to boats describes a couple of chemical phenomenon that causes resins and laminates to deteriorate. There is a lot of good (and bad) information to be had on this subject.

Water intrusion into cores causes wood rot and debonding of the wood core. Intrusion into a debonded foam core will worsen after freezes so even there it is to be avoided.

Water absorption is not the same thing. Most plastics and resins will absorb water, especially nylon and epoxies. I have not looked, but would bet a beer that Coosa and other such foams will too, but as Jim said, not very much. And they will not rot. Some friable foams might start to deteriorate if very wet, but these and not what you will be using for a core.

Bobk