screws or rivets

[Pell]

I have read some about the use of screws to attach planks to frames instead of rivets.I wish to screw instead of rivet my planks to frames.My planks are 7/16 sp cedar over 3/4 oak.It seams hole size of rivet being smaller is better yetthe time would be imense to rivet. Am I just wimping out coming to realize how much time can go into her. Also Is it silly to do my scarphs in polyurethane instead of epoxy.Heat of shop is an issue.Thanks for any advice

[W. Marks]

Rivets typically on planking that thin, less chance of splitting planking & frames. As far as glue have no experience with poly.

[Thad]

Rivets are clamps, screws are curved incline planes of wedges. Copper is ductile, silicon bronze is ridgid. In the wetting drying situation and use of most boats, rivets accomodate the movements of planks and backbone easier than screws. Properly installed screws however can work well for over 60 years. What are you building?

[Ross M]

There is a pretty good discussion of the screw vs rivet subject here: Repost "Screws vs. Rivets" (http://media5.hypernet.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic;f=1;t=005870)

As regards PU vs Epoxy for scarfs, you might spend some time perusing WB FAQ Building and Repair, ver. 2.0 (http://media5.hypernet.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=008298) . This seems to be one place where I personally would prefer the stiffness of epoxy to the elasticity of PU. Hopefully someone more experienced will pipe up shortly.

Ross

[Cuyahoga Chuck]

Pell,
I'm surprised that this topic still comes up. Polyester resin (I think that is what you meant) went out with high button shoes. Polyester is still used for making entire boat hulls (it's cheaper)but comes the time to patch polyester you have to use EPOXY.
The only folks who vilify epoxy are those true believers who want everyone to go back to clinch nailing and rivit setting.
God bless them but epoxy is the answer for those of us who can't afford a hammer and a dolly.
Charlie

[Pell]

Thanks for the advice I knew rivets were the way and epoxy but I was trying to cheap out.It seems rather difficult to rivet the heads on the inside building the boat upside down.I guess it has to be done peens outside and :confused: countersunk?

[Wooden Boat Fittings]

No, no. Peen the inside only. Dolly always on the outside. Use four hands -- hell, sign on a crew -- if necessary.

Mike

[TimothyB]

Originally posted by Cuyahoga Chuck:
*snip*
The only folks who vilify epoxy are those true believers who want everyone to go back to clinch nailing and rivit setting.
God bless them but epoxy is the answer for those of us who can't afford a hammer and a dolly.
CharlieWell.. I don't think this is entirely true. Epoxy is a way to save on labor, but only in the sense that you don't have to be as skilled to get a good result. A skilled boatwright can knock together a traditionally constructed boat in less time than an 'unskilled' one can put together an epoxy boat. Basically, the FG revolution was due to two things:

1) You can use unskilled labor to layup boats on molds, which brings down the cost of production and allows for mass production much more easily
2) FG is perceived as a low maintenance material

Both of these things lever into epoxy construction of wooden boats as well. It takes less skill to make up an epoxy boat than a traditional one, although it does take some skill to do it well. And epoxy construction is perceived as a low maintenance and 'safer' method. This because 'wood rots'.. in other words a badly maintained FG boat will sink less often than a badly maintained wooden boat.

Lets remember how much marine epoxy costs.. 10s gallons of it (sometimes 100+ gallons) are used to build larger boats, and that is EXPENSIVE. The real savings is in training/labor costs, or if you are using cold molding to abate a wooden boat's hull that needs an overhaul. In that case rather than replace frames and planks you are definitely saving some money and LOTS of time by cold molding a new hull over the old one.

I don't think epoxy material costs scale with size anywhere near as well as fasteners and wood stock, considering large timbers can be had cheaply if you laminate them up from rough sawn stock yourself, and I think decent planking wood can still be had if you are willing to buy them in the log. Bronze fasteners are now available at lower prices as well, and bulk discounts are easily had by a boatwright, or even a backyard builder.

The real advantage of epoxy is in its ability to seal wood grain which slows the incursion of moisture to a crawl, and in that regard I don't know of a less expensive way to coat wood surfaces given the effect provided, however it still costs more up front to do than oil paint.

So, I don't think epoxy is a cost saving measure as much as it is a time/skill saving measure. Glued plywood lapstrake is easier in a lot of ways than traditional, and cold molding up with plywood or veneers is certainly easier than planking but the material costs will be higher now that lumber prices are seemingly more attractive than plywood prices.

Personally, I will use epoxy wherever I think it makes sense, but I don't believe it is a cost saving measure.

--T