I have used the GoPro suction mount on many occasions, even bashing through surf. It has never come loose. I guess one will need to keep an eye on corrosion on the bolts though. I spray WD40 on mine now and again.
I use the suction cup on the front of my Stellars but yes they have a flat surface, have not tried on a curved surface. GoPro have stick on mounts that work very well and I use these on my sea kayak, also have these stuck inside the front of my cockpit and at the rear of my Stellar as well, always tether the camera just in case regardless of what you use. The stick on mounts come in flat and slightly curved so they will work on any ski. Just need to tighten the mounting screws with a philips head screw driver if punching out into waves otherwise the camera can get knocked over on its mounting screws and you will get nice video of your deck.
Yes the GoPro suction cups work well on flattish surfaces, but just to be sure fast moving water doesn't force the outer rubber lip up and compromise the vacuum, seal the cup to the deck/upper hull with a few layers of duct tape. Tether always, a spare stick on mount is good as a tether point, make short as possible.
I used to tether back to the cockpit but found after few times when a camera has detached (usually while surfing a sizeable wave) the camera does considerable damage to the hull from a long tether. A short tether ( right next to the main mount) keeps the camera close to the craft and out of most of the waters force. It's an easy dismount to remove it.
A friend of mine does a lot of composite work. He let me have some scraps of carbon and foam to make these camera mounts. These are my first attempt at composite work, so it took me a LONG time. I'm a woodworker by trade and have a lot of respect for composite guys. Tricky stuff to work with. But the foam machines just like wood. So, nice smooth transitions with some saws, files and sandpaper. Fun project for me.
The results are amazing. 2 layers of carbon, pre-wet on a table and carefully laid on the boat or over the foam. Both mounts are exceptionally light. Super strong. I secure them to the boat with clear packing tape. Exceptionally secure, no need for a tether in the front. Skin tight fit to the hull. No tape in these pics. The rear mount is about a foot off the deck. Thin unidirectional tubing.
IMO, thin tubes and smooth transitions are important out back. I've tried suction cups with wood prototypes and felt it steering the boat.
Also, the deflector on the front mount is necessary. I tried it without - the cam would just lay down. My south shore runs start with zero fetch. Tight bumps early on. So sometimes I need to ram through stuff. If I err on the north shore and jam the nose, no worries. It's raked to help lift the nose.
GoPro adhesive mount works a treat on my Fenn, slightly angled deck but have nearly total adhesion. Have it tethered to the small adhesive safety bracket as well. Also have the orange float pad attached. No problems so far and it has copped a good workout on occasions.
LaPerouseBay, I've been thinkig of something similar to your rear mount. I want to place the cam higher than deck level and I don't want the cam to move a lot. I'm sure the tripod is the way to go. Where do you get your thin tubes ? What are they sold for ?
Hiro, the tubes are 8mm, unidirectional. No idea where they came from or what they are used for. Mike gave them to me and someone gave them to him. If you google carbon fiber tubing you will get several suppliers. Mike says they are fragile, so I coated them with epoxy.
About a foot off the deck works ok for me. Any higher and I worry about the swing weight. Too low and the cam is always underwater.