Get the Hole Saw, No Flat Wood Bits.

Rookie move learing the hardway, trying to save a buck,  so I thought I'd share.

In mounting some rod holders I found out the hard way never to use one of those flat wood bits.

Spend the extra $ on the Hole Saw or if big enough use a jig saw.  The Flat wood bit will start out OK with a pilot hole but then tear more of a non-circluar hole when it punches through unevenly. 

Luckilly the rod holder flange, gasket and marine goop took care of it, but a tighter fit would have been better.

I always go one size smaller on the hole saw than needed for my "big" holes. I then take a round file and enlarge slightly, use heat gun to 'warm' the plastic. Next marine goop object and insert. Drill and rivet while the goop is still wet.

-Brian G

Yup, I've made the same mistake. This is a good reminder. It's all about the hole saw bit. And for flush-mount holders, the hole needs to be oval-shaped, so I use a small knife to carve the circular hole outwards---shaving small pieces at a time.

I was lucky, I've had a full set of hole saws for years (got them as a present).  So my hole cutting has come out prett well. Otherwise as tight as I am, I'd have tried the paddle bit as well to save a buck. Some one asked me not to long ago if I thought a paddle bit would work on plastic, I loaned them a hole saw.  Actually I haven't gotten it back back yet, thanks for the reminder.

Dale L

I've used the wood bits quite a few times and haven't had a problem, but the trick is to drill slow with light pressure and use a size or two smaller. Then I finish it off with a file or like Brian said the file & heat gun.

The biggest thing to keep in mind, like Sin Coast said flush mounts with an angle requires more of an oblong hole instead of a round, just remember this when your drilling & placement.Don't forget to goop you rivet holes as well. 

I've put in oblong holes for flush mounts and some big holes for hatches.  I just use my jig saw with a fine tooth blade.  it's pretty accurate.  I could see how those spade bits could be a problem on smaller holes.

Try Forstner bits, unless the required hole is just too big. They do a great job on kayaks, even the el cheapo sets from places like Horrible Freight (mine's better than that, but all of them will do the job).

I've used a Rotozip saw to cut holes for my fishfinder install and it worked well...  kinda squirrelly, though, easy to get out of control if you're not paying attention.

I've used a Rotozip saw to cut holes for my fishfinder install and it worked well...  kinda squirrelly, though, easy to get out of control if you're not paying attention.

Too easy to go out of control. not worth the risk IMO.