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BOARD nose modification ? strength ?
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dvCali



Joined: 23 Aug 2007
Posts: 1314

PostPosted: Fri Sep 27, 2013 9:09 pm    Post subject: Reply with quote

thombiz wrote:

b. Use a router with a plow bit to remove the outer reinforcing and most of the high density foam for a distance of about 3" from where you cut the nose off. Be careful to set the plow depth so that it does not cut the reinforing fiber between the outer high density foam and the styrofoam.

Hi Bob, similar winter project here (but later: fall wind has been good!). Just wandering: why go through the complication of the router instead of simply sanding the 3" area from the cut and glassing over to the new front with 4oz S-glass?
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dllee



Joined: 03 Jul 2009
Posts: 5328
Location: East Bay

PostPosted: Fri Sep 27, 2013 9:41 pm    Post subject: Reply with quote

I like sanding a bevel into the cut area, instead of routing, because I'm lazy and some very good board repair people do it that way.
A clean rout can make a better water seal, as the glass can butt into the L shaped notch.
But in practice, it seems a bevel can work just fine.
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thombiz



Joined: 25 Jun 2007
Posts: 799
Location: Corpus Christi

PostPosted: Fri Sep 27, 2013 11:48 pm    Post subject: Reply with quote

The reason to cut back the high density foam is to expose and bond to the reinforcing between the high density foam and the styrofoam. Boards can delam in many ways, like heat, air pressure, etc. but one of the most common ways is to not have enough strength in the reinforcing between the high density foam and the styrofoam. A shortage of reinforcing allows the high density foam to deflect too much under load damaging the styrofoam. In this case, (remaking the nose) the possibility of mast whacks is very very high. Extra reinforcing will turn mast whacks into dents instead of breaks and cracks. High density foam can be incredibly strong and durable if you give it enough reinforcing. I've worked on a number of commercial boards with reinforcing in the .7 oz to 1.4 oz. range. This gives the the boards a very light weight at the cost of a short lifespan. You don't have to go overboard with reinforcing. I use 6 oz s-glass or 6 oz carbon in the footstrap area and 4 oz. s-glass or carbon in all other areas between the high density foam and the styrofoam. I usually double layer on the frontmost 16" of the nose. I've never had a delam on the boards I've built, even after 5 or 6 years and I weigh 225 lbs and sail some pretty rough water.

I have no problem with a tapered joint, I just happen to be better at making square joints.
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thombiz



Joined: 25 Jun 2007
Posts: 799
Location: Corpus Christi

PostPosted: Sun Sep 29, 2013 10:29 am    Post subject: Reply with quote

Finally remembered the name of the styrofoam adhesive recommended on Swaylocks........Foam-Lok See: http://www.amazon.com/Foam-Lok-Adhesive-Can-17-25/dp/B004IAKX46
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Tue Oct 01, 2013 2:43 pm    Post subject: Reply with quote

thombiz wrote:

b. Use a router with a plow bit to remove the outer reinforcing and most of the high density foam for a distance of about 3" from where you cut the nose off. Be careful to set the plow depth so that it does not cut the reinforing fiber between the outer high density foam and the styrofoam. You can sand any high density foam down to just above the reinforcing.
c. Sand smooth the styrofoam where the new addition will be added. Use a styrofoam bonding glue to bond the new styrofoam to the existing styrofoam. If in doubt on which glue to use, check Swaylocks. Bond the new to the existing.


Bob T.


Confused on the "plow router bit" bit, is the bit called something else perhaps,other than plow.
Square cut off the nose..then is it joined like a dovetail or similar ?

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dllee



Joined: 03 Jul 2009
Posts: 5328
Location: East Bay

PostPosted: Tue Oct 01, 2013 4:18 pm    Post subject: Reply with quote

Seems to me, any router bit does the job just fine.
You're only cutting 3/16" groove depth into the Dcell, so you increase bearing surface for a complete waterseal.
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thombiz



Joined: 25 Jun 2007
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Location: Corpus Christi

PostPosted: Tue Oct 01, 2013 5:57 pm    Post subject: Reply with quote

A picture is worth a thousand words: this is what I would use
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U2U2U2



Joined: 06 Jul 2001
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Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Tue Oct 01, 2013 6:02 pm    Post subject: Reply with quote

got it. thx
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dllee



Joined: 03 Jul 2009
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Location: East Bay

PostPosted: Tue Oct 01, 2013 9:44 pm    Post subject: Reply with quote

Looks like the bit in the router I last used.
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Thu Oct 03, 2013 2:14 pm    Post subject: Reply with quote

extreme swallow tail or squash ?

need a source for foot pads, and best glue ?

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