Stem Question

So I’ve been working on the stem recently and decided to dado a slot to accept the ¼” ply.  My question is how to finish the stem.  I plan to oil the interior of the boat along with the stem and now I’m wondering why I shouldn’t oil the exterior of the stem as well.  I suppose I’ll have to epoxy the dado slot so the 5200 will adhere to both the stem and side panel, but can the leading edge be oiled?  I keep reading about the danger of using epoxy, cracking it and allowing water in.  I rowed a barge down the Deschutes last weekend and suspect my stem will take a beating until I’m a little more proficient with the oars.  So is everyone using epoxy for the whole stem and stem caps?  Am I crazy for wanting to use oil on this piece of the boat?  Thoughts?

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Permalink Reply by Guy Fredrickson on June 3, 2012 at 5:38pm

Awesome woodwork!

I met several people (builders) at the Wilson Boat Show, who convinced me of the following.

1) I will install a strong (white oak) chine cap on the exterior of the boat.

2) I will fasten a metal bumper-strip (silicon bronze, stainless steel, or aluminum) to the chine cap for extra protection.

3) The chine caps will be fastened with 3M 5200 and a few wood screws into the chine logs.

I am going to fiberglass and paint the outside of my boat.  AJ's son (I can't remember his name) recommended that I do not lay fiberglass underneath the chine cap and that I let the 3M 5200 make the seal between the side panel, bottom panel, and chine cap (which covers this seam).  I have not yet decided what I'll do.  I was planning to lay an extra layer of fiberglass over this seam, which is contrary to this advice.

Anyway, I think how you finish your stem post is dependent on how you finish the rest of the boat's exterior.  You can always protect the lower portion of the stem post with a metal bumper-strip.

Permalink Reply by AJ DeRosa on June 4, 2012 at 11:38am

Guy,

Points one and two on your list of things learned at the boat show are spot on.  Point three needs to be addressed.  3M 5200 is a polyurethane based marine adhesive.  Once applied it will be very difficult to remove.  Like epoxy it is stronger than the surrounding wood so you will break the wood before you break the bond.  A chine cap is intended to be a sacraficial piece.  It takes the abuse of repeated hits and in time needs to be replaced.  A polysulfide marine bedding compound like Sika flex or Boatlife's product is the right stuff for this application.  It remains flexable and creates the water tight seal that you want on your chine joint.  It makes the replacement of the chine cap a very easy project.  3M 5200 is best used in bedding the inside chine log and to bed the bottom panels to frames and edges.  These parts, when properly installed and protected, are most likely there for the life of the boat.

 

My "son's" advice about not glassing over the chine joint is good advice.  The marine bedding will seal this joint much better than fiberglass that can become cracked and then weep moisture into the joint.  There are those who prefer to run fiber glass over both the joint and the bottom edge.  Both methods are being used by different buiders.  I prefer the former.  Check back through the archives as this has been addressed in the past.

 

By the way, for those of you who know that I don't have children,  my guides are sometimes refered to as my "sons".  Especially Dutch and Kevin who spent 6 years in my back pocket and soaked up everything that they learned from myself and the legendary builders that we hang out with here and in Oregon.  Yeah they are just like sons, sometimes a pain in the arse but for the most part I am proud of them and happy to have a passionate and capable crew to take over down the road.  They know what they are talking about.

Permalink Reply by Guy Fredrickson on June 4, 2012 at 4:37pm

AJ,

Thank you very much for the clarifications.

Guy

Permalink Reply by Mike Baker on June 3, 2012 at 6:30pm

Hey Nick,

I do my stems the same way you are doing yours. I usually finish the outside of the stem the same as the outside of the boat, so typically I will epoxy it and then varnish over that. I see no problem if you want to oil the whole piece. Epoxy does not stick especially well to oak anyway and if it is going to take a beating oil will be easier to repair. There is no need to epoxy the slot for the 5200 it will stick just fine. You can also use epoxy on that joint instead of 5200 ( that is what I do).

Mike

Permalink Reply by Nick N on June 4, 2012 at 5:16pm

Thanks for all the info.  I suppose I didn't put two and two together about 5200 sticking to oiled pieces.  I have certainly read about oiled chines adhered with 5200.  I'm assuming the same holds true for the Sika Flex AJ referred to?  I purchased some for the same reasons he mentions.  I think I'll plan to oil the whole stem then.  The seats and a couple other pieces are oiled Mahogany and this way they'll match the stem(also Mahogany), sort of bringing the outside and inside pieces together.

Guy, I've contemplated the metal bumper(stem or chine) and I'm probably not going to go that route for a couple reasons.  First, I think it will ad some weight I don't need and second, while I plane to use/abuse the boat I won't be able to fish it enough to really kick the snot out of it.  I think simple maintenance and eventually replacing the chine are in my future, though hopefully the replacement will be some years down the road.  If I'm wrong I can always add the metal on the new chine!  As for the compliment on the woodworking I credit the 6" jointer, a tool my better half is convinced is useless.

Permalink Reply by Mike Baker on June 4, 2012 at 6:34pm

Hey Nick,

Glue the stem to the side panels before you oil the piece. Same for the chine oil it after you glue and screw.

Mike

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