Cockpit Floor Re-Core question

This is the place to post your ideas, thoughts, questions and comments as relates to general boatbuilding and reconstruction techniques and procedures (i.e. recoring, epoxy, fiberglass, wood, etc.)
Post Reply
User avatar
preserved_killick
Skilled Systems Installer
Posts: 220
Joined: Wed Oct 24, 2007 8:01 am
Boat Name: Seagrass
Boat Type: Alberg 30
Location: NH
Contact:

Cockpit Floor Re-Core question

Post by preserved_killick »

Hi Everyone,

It's been some time since I've posted here. I've been simply enjoying the boat, and dealing with non boat projects.

The cockpit floor of my Alberg 30 is soft, and needs to be dealt with. What I'd like to do (other than ignore it) is to carefully cut the top fiberglass skin with some precise tool like a multi-tool or rotozip, re-core, then reuse the top fiberglass skin. Possible??? The fiberglass top skin has nice molded divits for the drains, a little volcano bump for the rudder shaft and the non-skid pattern is molded nicely around these. Many of the detailed accounts I've read so far describe a new fiberglass floor.
Am I dreaming?
___________________________________
1965 Alberg 30 #116
http://picasaweb.google.com/fongemie
Tallystick
Skilled Systems Installer
Posts: 177
Joined: Fri Sep 09, 2011 10:54 am
Boat Name: Nostalgia
Boat Type: Pearson Triton Yawl

Re: Cockpit Floor Re-Core question

Post by Tallystick »

I tried using a rotozip for cutting out the top layer of my fiberglass deck, and didn't have good results. An angle grinder with a diamond cutting wheel works much much better. You just have to be a little careful not to cut to deep. It's not that difficult really.

You may not need to cut out the drains or the rudder shaft bump. Cut close to them, remove the coring material, and slide the new material into the slots. I wouldn't try to reuse the top skin unless you can get it out in one piece. If you cut it out in sections, you would still need to more layers of fiberglass back over it. Fiberglass and epoxy are cheap enough that you may as well use new material. That will likely save you a lot of time sanding and fairing the repair.
User avatar
preserved_killick
Skilled Systems Installer
Posts: 220
Joined: Wed Oct 24, 2007 8:01 am
Boat Name: Seagrass
Boat Type: Alberg 30
Location: NH
Contact:

Re: Cockpit Floor Re-Core question

Post by preserved_killick »

Would an oscillating multi-tool work well for cutting the top fiberglass skin? I wouldn't mind a reason to buy one.

-Jeff
___________________________________
1965 Alberg 30 #116
http://picasaweb.google.com/fongemie
Tallystick
Skilled Systems Installer
Posts: 177
Joined: Fri Sep 09, 2011 10:54 am
Boat Name: Nostalgia
Boat Type: Pearson Triton Yawl

Re: Cockpit Floor Re-Core question

Post by Tallystick »

Nope, I tried that and cut through a few inches and the blade was shot. Just buy a cheap 4 1/2" angle grinder and diamond wheel. You'll be happy you did. They aren't very expensive.
bhartley
Skilled Systems Installer
Posts: 164
Joined: Mon Nov 21, 2005 3:13 pm
Boat Name: Ariel Pyxis
Boat Type: Sea Sprite 23 Cape Dory 25D
Location: Wolfskin Georgia

Re: Cockpit Floor Re-Core question

Post by bhartley »

I actually had great results with my oscillating saw. I did a total deck recore with 2 blades. I cut the top skins with plunge cuts and then used the same blade to clean up the rotten core and left over debris. I just used the sanding attachment to tidy up my toe/rub rails and grab rails for refinishing. I am loving it. Last boat I used a panel saw (3" circular saw) and it was a lot harder to get in to the edges I needed to reach. I bought the basic Rockwell Sonic Crafter at Lowes.
User avatar
preserved_killick
Skilled Systems Installer
Posts: 220
Joined: Wed Oct 24, 2007 8:01 am
Boat Name: Seagrass
Boat Type: Alberg 30
Location: NH
Contact:

Re: Cockpit Floor Re-Core question

Post by preserved_killick »

bhartley wrote:I actually had great results with my oscillating saw. I did a total deck recore with 2 blades. I cut the top skins with plunge cuts and then used the same blade to clean up the rotten core and left over debris. I just used the sanding attachment to tidy up my toe/rub rails and grab rails for refinishing. I am loving it. Last boat I used a panel saw (3" circular saw) and it was a lot harder to get in to the edges I needed to reach. I bought the basic Rockwell Sonic Crafter at Lowes.
Which blade? I know little about them. How slow is the cutting?
___________________________________
1965 Alberg 30 #116
http://picasaweb.google.com/fongemie
Quetzalsailor
Master of the Arcane
Posts: 1100
Joined: Fri Aug 26, 2005 9:53 am
Boat Name: Quetzal
Boat Type: LeComte North East 38
Location: Philadelphia, PA

Re: Cockpit Floor Re-Core question

Post by Quetzalsailor »

Glad to see you back, PK! I'm re-reading my O'Brien and enjoying 'em mightily.

Anyway, I did the cockpit floor in our previous boat, a Morgan 27. It had balsa core. I worked from underneath while the engine was on R&R getting an upper end rebuild. I used an angle grinder and, while it was fast and easy, it was a perfectly miserable job! I made the new core with 1/2" plywood and 'glass and then tabbed the assembly in. What a miserable job! I wore a plastic garbage bag to reduce the chance of my being bonded into the boat.

Working from the top, I think you could use an angle grinder with thin blades as available from the Despot. They're 1/16" or 1mm thick, depending upon the manufacturer and can be had for metals or masonry. You could cut the straight lines with an edge guide and cut the corners with a Fein or similar Multitool. The issue would be, since sloth is always good, how to make the replaced skin as structurally good as it was.

I've seen an article about this: No doubt you could scarph the joint but then you'd have to clean up the mess. Another choice would be to hack the whole thing out in one go, hopefully at a place where the flat floor meets the curved corners so that you would be removing all the cored area. Then bond a ledge onto the bottom of the perimeter and drop a rebuilt floor in. This could be forever re-removable for happier access to never-neverland below.
J.P.
Bottom Sanding Grunt
Posts: 7
Joined: Wed Jul 20, 2011 6:22 pm
Boat Type: Vivacity 20'

Re: Cockpit Floor Re-Core question

Post by J.P. »

Hi Jeff,
I am rather new at the forum, and at sailboat restoration in general, but perhaps just a circular saw with a good blade would be the ticket (I used to frame houses for a living, so I tend to think that a circular saw can do anything). I have used a circular saw set at a shallow depth to cut precise holes in fiberglass, and it has worked great. I have used a Dremel, Grinders, and a jigsaw and they were all much more difficult to get a straight line. The only limiting factor with a circular saw would be sharp radius-work and any close-quarter work, since the typical fence on a circular saw is 1 1/2".
Anyway, that is my two bits.
Good Luck!
-the other Jeff
User avatar
preserved_killick
Skilled Systems Installer
Posts: 220
Joined: Wed Oct 24, 2007 8:01 am
Boat Name: Seagrass
Boat Type: Alberg 30
Location: NH
Contact:

Re: Cockpit Floor Re-Core question

Post by preserved_killick »

Thanks guys.

About the Circular Saw: I was thinking one of those battery operated mini circular saws might be the thing, but I no longer own one. The one I has was great for a couple of weeks until it died. I think I'll get an oscillating tool, and a thin wheel for my grinder. Not really looking forward to this, but like many projects the hardest part is starting.
___________________________________
1965 Alberg 30 #116
http://picasaweb.google.com/fongemie
bhartley
Skilled Systems Installer
Posts: 164
Joined: Mon Nov 21, 2005 3:13 pm
Boat Name: Ariel Pyxis
Boat Type: Sea Sprite 23 Cape Dory 25D
Location: Wolfskin Georgia

Re: Cockpit Floor Re-Core question

Post by bhartley »

For my decks I used a 1-3/8" Metal/Wood Universal Cutting Blade. A very straight line is easy as you make repeated plunge cuts. It took a few seconds to make each cut and you could feel when you were through the top layer. I used tape to clearly mark the area to be excised and simply followed the line with successive cuts. I am working on a Cape Dory which has substantial decks and I was pleased with the results.
Tallystick
Skilled Systems Installer
Posts: 177
Joined: Fri Sep 09, 2011 10:54 am
Boat Name: Nostalgia
Boat Type: Pearson Triton Yawl

Re: Cockpit Floor Re-Core question

Post by Tallystick »

One of these on an angle grinder is the way to go. Cuts fiberglass like butter.

http://www.lowes.com/pd_195223-10742-TB ... facetInfo=
boatsnh
Rough Carpentry Apprentice
Posts: 61
Joined: Mon Feb 02, 2009 6:55 pm
Boat Name: IRIS
Boat Type: Dickerson 36 Ketch
Location: Concord, NH

Re: Cockpit Floor Re-Core question

Post by boatsnh »

I "second/third" diamond cutting tools...For the cost, they are a great value. Cut like the dickins & last a Loooong time.....I'm sure you could fabricate a "depth saddle" to sit the angle grinder in to only allow it to cut, say 1/4 inch deep. Lots of decent quality/inexpensive die grinders out there - definitely a full face protection tool....

Another thought, but harder to control, is a 1/4 inch high speed grinder with a titaniumNitride coated rasp...(titaniumNitride lasts 20 times longer than plain old high speed steel) this also gets in close & removes material at an astounding rate (spins at 25,000 rpm)...I've used one in a "saddle" I've dragged along a "line" to do pretty much wat you are looking to do...worked OK. Still like the die grinder & diamond wheel - a bit faster & a thinner "cut thru" line.. At the time I did not own a die grinder & had to "make do"...
Tallystick
Skilled Systems Installer
Posts: 177
Joined: Fri Sep 09, 2011 10:54 am
Boat Name: Nostalgia
Boat Type: Pearson Triton Yawl

Re: Cockpit Floor Re-Core question

Post by Tallystick »

This diamond rotozip tool also works great on fiberglass for areas a circular diamond blade can't get to.

http://www.amazon.com/Rotozip-XB-FT1-4- ... B000Y1EBM8

It's got a 1/4" shaft so not much worry about the shaft snapping.
Zach
Boat Obsession Medal Finalist
Posts: 684
Joined: Wed Jan 25, 2006 6:28 pm
Location: Beaufort, North Carolina
Contact:

Re: Cockpit Floor Re-Core question

Post by Zach »

You can save the top skin for re-use but it is more work. You will lose the non-skid outline and texture. You will have to drill a whole bunch of holes for the excess epoxy to get through. Even then it will not be bonded as strongly to the core as new work, and will be softer feeling under foot than new work. To get it to pull down, it is best to use screws and fender washers, but with balsa core (if you use it) the underside holes have to be filled too or it will wick in moisture.

I would start by laying a 1 1/2 inch straight edge down along the edge of the non-skid well away from the fillets in the corners, I often follow the edge of the non-skid. Sharpie the line around everything. Going around something rounded I use a small block to mirror the line out. Take a sheet of paper or tar paper and put it down on the deck, and cut it out along the lines, or mirror it in 1 1/2 inches. When you cut your core and glass you have the pattern Make the core a slight bit smaller than the template. Normally glass on these boats is a 1/4 or 3/16ths thick on the decks. That means 3 layers of 1708, 2 makes an 8th inch.

Your paper template is the template for the glass. The top piece is the paper, the middle piece is 1/2 inch bigger on all sides. The first piece is 3/4 bigger. Saves on grinding, rather than cutting them all the same size and trying to level it out later.

Actually, it should be noted that grinding the bevel flat, you almost can't go to far to get the taper on the outside edge flat on the new glass work. Otherwise you end up with a bump, and will chase your tail floating it with fairing compound. When working with the faring compound after the glass work is done, cut a stick of 3/4 plywood 2-3 inches tall the width of the cockpit sole and pull it, if it takes 2-3 sticks so be it... That will get the floor as flat as the old floor, fast.

When you get close to the tiller head opening, don't be afraid of cutting some 2 inch strips by 4 inch long out of the same glass you are using, and strip in around it if the second and third layers don't want to co-operate. You can also cut a dart, and rub your gloved hand vigorously back and forth to loosen up the cloth, if you are using biax.

Don't grind sand or mutilate the fillets in the corners. I often go so far as to put a few layers of blue tape in them so that a goof with the grinder isn't as deep... sometimes unscathed.

To remove the top skin, I use a 4.5 inch mini grinder with thin metal cut off wheels to cut through the fiberglass, leaving the sharpie line. Cheap, and they cut metal. I don't cut much concrete so the diamond ones don't have much allure to me.

Then I use a twisted wire stainless brush on same mini grinder to sling the majority of the punky core out. No gloves, as wire brushes and gloves are dangerous. Face shield... That which does not come out easily, gets multi-master scraped out. I try not to use the saw blade on them, because they are expensive and slow. The are worth their weight in gold for getting the excess out of the edge.

Then I use the mini-grinder with a plastic backup pad and 3M 36 grit discs to grind the last of the glue blobs and stubborn core.

Then with the mini grinder, I grind the bevel around the edge with a 36 grit flap disk, going from the non-skid edge to a feather where the sharpie line was. Bevel stays the same angle the whole way around.

For tight spaces, I have an adapter for my mini-grinder that accepts 3M roloc grinding discs. You can use a drill or die grinder too, but the 2-3 inch disc are often what the doctor ordered.

I like the small light weight hitachi's mini grinders for tight places, as you can bind them up and over power them. Dewalt or milwaukee with a dead man switch and 8-10 amps, for the heavy work.

Pick your core. I'd use perforated divinycell or core cell foam so it can't rot again. Pack the gap under your ground bevel with cabosil and epoxy. If the inner skin doesn't bow, you can use a sheet of thick painters plastic 4-6 mil and paint cans, bags of lead shot, sand... to smash the core down to the skin.

If you are using balsa, lay it over a drum or a large diameter piece of PVC pipe and let the epoxy run down the grooves so each block is coated with resin, and cannot track water between them. The core bedding epoxy is not paste, but thick enough when you pour it out of the cup it piles up like ice cream. Notched trowel the epoxy out. Plop in the core and smash it down with your hands trying to work the excess air out from under it from between the sheets.

Let the core kick off, keep the pot you used to mix the resin and when the thin film at the top has gone one step past gummy and is no longer sticky you can take off the weight and start laying fiberglass. You should do this on anything structural and use a new pot leaving the old in order, in the event you have a bad batch of resin or hardener somehow you can work through where it happened.

You have 4-5 hours before the amine blush starts to form on epoxy, so this can be a grind it out in morning, acetone and glue in the new core at lunch, and be laying fiberglass in the afternoon. You want your core hot as you are applying the epoxy and cooling off, so that it absorbs the liquid resin instead of releasing the air trapped in it as it warms, makes or better looking glass work. You can put it back in the sun after the epoxy has gelled up for an hour or two, otherwise you will be air rolling the bubbles back down. Just try to lay it all up well before the dew starts falling, or the epoxy will blush...

I like to either resin coat the glass work twice... IE let it gel, roll on a coat of resin, let that gel, and roll on a second. Or apply a layer of adtech proseal after the glass work has gelled. You can get by with a very well homogenous mix of a somewhat runny coat of west systems 407 with just enough cabosil mixed in that the resin doesn't separate.

Zach
1961 Pearson Triton
http://pylasteki.blogspot.com/
1942 Coast Guard Cutter - Rebuild
http://83footernoel.blogspot.com/
mitiempo
Candidate for Boat-Obsession Medal
Posts: 319
Joined: Mon Oct 27, 2008 11:37 am
Boat Name: Mi Tiempo
Boat Type: Canadian Sailcraft CS27
Location: victoria bc canada

Re: Cockpit Floor Re-Core question

Post by mitiempo »

The only suggestion I would make is to make the first layer of biax the largest, and then progressively smaller. This prevents the important part which overlaps the ground taper at the edge from being sanded through when fairing. Here is a link on Tim's site showing exactly that. http://www.lackeysailing.com/snowlily/2 ... /32312.htm
User avatar
preserved_killick
Skilled Systems Installer
Posts: 220
Joined: Wed Oct 24, 2007 8:01 am
Boat Name: Seagrass
Boat Type: Alberg 30
Location: NH
Contact:

Re: Cockpit Floor Re-Core question

Post by preserved_killick »

Zach,

Thanks for taking the time to reply. I've been reading through it, and re-reading to be sure I understand it all, and researching the details. Where to get stuff etc.

-jeff
___________________________________
1965 Alberg 30 #116
http://picasaweb.google.com/fongemie
User avatar
preserved_killick
Skilled Systems Installer
Posts: 220
Joined: Wed Oct 24, 2007 8:01 am
Boat Name: Seagrass
Boat Type: Alberg 30
Location: NH
Contact:

Re: Cockpit Floor Re-Core question

Post by preserved_killick »

I'd really like to save the topskin, but in the event that I can't..I'm working out the details on rebuilding the top layer of glass.

My primary concern, is what to do with the volcano bump that rises up for the tiller. Could I cut the volcano out of the old top skin, bevel the edges and use it in the new fiberglass top? Seems it would be difficult to reproduce this.


Image

Also, anyone know a source of core materials in Maine? I can get marine ply, but can't find balsa or any good foam cores. Hamilton's does not list any in the catalog.

-jeff
___________________________________
1965 Alberg 30 #116
http://picasaweb.google.com/fongemie
boatsnh
Rough Carpentry Apprentice
Posts: 61
Joined: Mon Feb 02, 2009 6:55 pm
Boat Name: IRIS
Boat Type: Dickerson 36 Ketch
Location: Concord, NH

Re: Cockpit Floor Re-Core question

Post by boatsnh »

Sure you can save - re use that piece. It's just a function of cutting out tube with a reasonable (say 12") radius to alow you to feather that in to your new deck top skin. I think the ratio is something like 1:10 or 1:12 to feather for good bond strength...so a .25 inch thickness needs 2.5 to 3 inches of "feather" into the new work. Not a difficult job. Thats for the "outer" part of the tube....what does the inside of the tube look like?? I'd be interested to see how/what kind of glass layup is in place now...lots of torque on a rudder tube.....You want to make sure that the tube retains all it's strength at the top......I'm pretty sure Jamestown carries Balsa core material & will UPS to NH. Matt (Alberg 35 MAGIC) got some for his job in Canterbury....Perhaps he will pipe in, or tag him an e-mail...
MikeD
Candidate for Boat-Obsession Medal
Posts: 375
Joined: Wed Aug 24, 2005 1:42 pm
Boat Name: Totoro
Boat Type: Sea Sprite 23 (#626)
Location: Scarborough, Maine

Re: Cockpit Floor Re-Core question

Post by MikeD »

I got my corecell from Noah's Marine (http://www.noahsmarine.com/) a few years back.

Here's their core materials page: http://www.noahsboatbuilding.com/items. ... POSITE&Bc=
Mike
Totoro (SS23 #626)
Zach
Boat Obsession Medal Finalist
Posts: 684
Joined: Wed Jan 25, 2006 6:28 pm
Location: Beaufort, North Carolina
Contact:

Re: Cockpit Floor Re-Core question

Post by Zach »

Measure the cockpit sole, I may have a piece of 1/2 inch corecell around that size laying around.

Fret not the volcano bump.

Cut the top skin off around it! 2-3 inches off the outside of the bump. Route out the core material that is in there, pack it full of epoxy and cabosil, grind the bevel around the top and lay the new core and fiberglass.

I'd run a 1/4 inch drill through the deck around the volcano bump to see if the core extends all the way to it, or if it is solid glass extending out a good distance.

Don't cut the rudder tube and try to glass it back together. It won't be straight unless you have a pipe or guide that fits inside it to hold it perfectly true. If it fits that tight, you won't get the guide back out without a fight. Even polished waxed pipe doesn't release very well as very few things in this world are perfectly round. You have to have rubber mallets, and enough room to hammer the pipe out of the inside of the fiberglass tube.

Zach
1961 Pearson Triton
http://pylasteki.blogspot.com/
1942 Coast Guard Cutter - Rebuild
http://83footernoel.blogspot.com/
Quetzalsailor
Master of the Arcane
Posts: 1100
Joined: Fri Aug 26, 2005 9:53 am
Boat Name: Quetzal
Boat Type: LeComte North East 38
Location: Philadelphia, PA

Re: Cockpit Floor Re-Core question

Post by Quetzalsailor »

That cockpit is so huge I would not hesitate in whacking it out and putting the top skin back. Plenty of space within which to work.
seasailor55
Rough Carpentry Apprentice
Posts: 57
Joined: Wed Aug 31, 2011 5:32 pm
Boat Type: Cape Dory 22 Pearson Ensign

Re: Cockpit Floor Re-Core question

Post by seasailor55 »

I just recored sections of a Cape Dory 22 deck that were soft, and the advice here is the best I've ever read. I was fortunate to be able to remove and save the top deck skin sections, as the balsa core was pretty much peanut butter. Using a 4" angle grinder with a 1/8" blade, I plunge cut areas larger than the soft spots, then removed the top skin using an oscillating tool and sawzall with a long flexible blade. The oscillating tool, a grinder, and a pad sander removed any remnants of the core (including 1" all the way around under the remaining deck). I cut the new balsa slightly oversize so I could slide part of it under the remaining deck, then set the balsa in with resin top and bottom and all around the edges. I set the cleaned and sanded resin coated top skin in place using 1/4" plywood covered with packing tape and paving stones to press it down in place. When it cured, I used a sanding disc on a 4" angle grinder to create a shallow groove all around over the cuts, laid strips of cloth tape and resin in the grooves, sanded these down and finished with epoxy fairing putty. While the putty was still soft, I repilcated the non-skid using an old towel to stamp a pattern as Cape Dory non-skid is fairly random with no definite pattern. Not saying this is the best way to do this, but it worked, was fairly simple, and not too terribly time consuming or messy.
galleywench
Skilled Systems Installer
Posts: 188
Joined: Mon Jan 05, 2009 10:21 pm
Boat Name: TBD
Boat Type: Rhodes 19
Location: Canterbury, NH
Contact:

Re: Cockpit Floor Re-Core question

Post by galleywench »

You shouldn't have any trouble with the 'volcano bump' and any other of the molded features you want to preserve (and not have to recreate). I had my own 'volcano bump' on the foredeck of my alberg 35 that I had the same concerns over. It was a raised section for a deck vent. I simply cut around it leaving a wide enough flange to grind a bevel. The actual fiberglass molding was molded through both the top and bottom skins so I didn't need to remove it and reset it when I recored.

Best explained in photos:
http://2.bp.blogspot.com/_t6lM2QPPif0/S ... 001142.jpg
http://4.bp.blogspot.com/_t6lM2QPPif0/S ... 001506.jpg
http://3.bp.blogspot.com/_t6lM2QPPif0/S ... 001349.jpg
http://2.bp.blogspot.com/_t6lM2QPPif0/S ... 02103a.jpg

and blog post:
http://www.alberg35.com/2010/04/recore-marathon.html

Hope this helps.
1963 Rhodes 19 #731
http://www.fernhollow.net
Post Reply