I'm I newbe to Striper Fishing, but I just go back from a week of vacation down the cape with the family and I got skunked at the canal.
There where reports at the B&T shop last week of a 25 and a 33 pound striper pulled from the canal. The bluefish have invaded the west side of the canal, so you want to stick to the middle and east end.
For a B&T shop, try Canal bait and tackle. It's located on off Route 6A. Here is the link http://www.canalbaitandtackle.com/
You can also buy bait at the Marine Supply store in Sandwich, it's next to Stop and Shop near the road to the Marina.
According to the locals, the best time to fish is from 2 hours before slack tide until about 1/2 after. You can get the info from the local paper or the bait and tackle shop.
Most people that I saw fishing where using chunk mackeral. All week I tried a spoon and 2-3oz bucktail jig with pork trailer. I was told plugs where working well.
I was fishing mostly on the East Jetty, lots of Fluke out there. There is also an occasional bluefish that loved any soft plastic you put out there. I was also fishing near the power plant. I was told the best spot to go is after the power plant next to where the oil tankers dock.
I took a bike ride with the kids on the last day and spoted a crowed near the channels where the power plant takes in and discharges water into the canal. TONS of Stripers in these channels. A couple keepers and ton of smaller ones directly under the bikepath and next to the building in the shade. We are talking 100s of them. Problem is, it's fenced in and you can't fish it.
One more thing, on humid morning with no wind, wear long pants and shirt while fishing on the canal. I went one morning at 4AM, I was attacked right when I left the car that I was dancing around just trying to tie on a lure. I put on deet and I think they liked it!!!!
Also, if you go at low tide, the rocks are VERY slippery. Be careful.
Best of luck, I hope this helps. Let me know if you have any luck.