Posts: 3508
Location: Elk River, Minnesota | Hiya!!
Adding a foil to an outboard is really only a band-aid to a set-up issue...mostly used for rigs that are underpowered. Underpowered rigs have a very hard time getting the boat up on plane because the power in the rear is not enough to push the rear upward with enough thrust. What the foils do is act like a wing on a plane....it creates more surface area on the top of the wing thus creating "lift." Just like a plane wing... The water traveling above the wing moves faster than that below the wing, thus creating a low pressure area, thus the rear lifts better.
The major downside on foils is that extra surface area as well...it takes away your top end speed unless you are underpowered. Most boats when they are set up have the motor too low on the transom. A properly set up rig will have the anti-ventilation plate just above the water line while on plane....in other words, it's not in the water creating drag. If you run a foil and your motor is all the way down on the transom, you are robbing your motor of speed as that foil will be running in the water. But...to keep the boat up on plane, that foil needs to be in the water. That is why underpowered boats work better having the foil.
Speed is not always the key element in boat set-up, though... Some people want the handling more so than speed, while others want speed over handling. Then there are those who love to tweak things and find a good happy medium.
No matter what you want out of your rig, a foil helps those boats that are significantly underpowered. If your motor is within 10 - 15% of your max boat HP, a foil should not be needed...In most cases set-up issues on boats is propeller related when the boat has a motor that is at or close to max HP.
Steve |
