Hi guys, looking for advice on outboard motors for tow ins with a lightweight 11ft inflatable dinghy. Does a 9.9hp 2 stroke have enough juice? 180 lb rider weight and 25 liters prone board. I would really like to avoid having to deal with the heavier 15hp.
I don’t experience with the inflatables. But the little dingy type boats in Bali with a 15hp are just enough to get me up on a small foil and small board(165#). I preferred 20hp or more.
If you are on a higher surface area board, it may be fine.
No, you won’t get up on a 25L board. I’ve tried with 25hp and a similar sized board, and we had to accelerate down wave to make it work. It was not good. Go with a big floaty board, like 70L+ and it can maybe work. Or get more power. A 15hp probably still won’t get the 25L board up. Your doing the same as wakeboarding+ dragging foil with that small of a board.
If you do a wakeboard sideways start it probably won’t be powerful enough.
If you can stand on the board while its sunken and float it up to the surface when you start. it might be enough
My 2 cents - its all about planing shape. I use a 4’4 21L Lift Bryan grubb with my tow boogie and can get up on any foil doing sinker start (foil size is almost irrelevant). 85kg
With the right planing shape you should be OK but if course more is more.
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Agree completely, once up to a little bit of speed, volume doesn’t matter as most of the lift is generated by the planing shape. A skimboard with less than 10L of volume can generate more lift than a 40L nugget board
I think you will need the 15 at least. My friend has a 9.9 and his RIB is pretty slow with him and his wife. I would do more research, a lower pitch prop would likely help and a planing iplate that you mount on the cavitation plate for the engine would also likely help. Hard to beat more power and a good planing board.
I think a 9.9 is fine if you have the right prop. If you can get a big low pitch prop you’ll tow up fine - but be frustrated with the low top speed when just driving the rib around.
Thanks for all the feedback guys - appreciated. I have previously towed with a 15hp on a big heavy dinghy which worked ok so long as the board was not too small surface area wise. Thinking about buying one of these dinghies from True Kit - it is really light like 35kg so was thinking the 9.9hp could do it. Seems to go pretty fast in the video. https://youtu.be/tJjn1kww6no?si=BixtvDofu-XPg93k
Garywaneshapes makes very large surface area 10L boards for pumpfoiling and he seems to have no trouble using them as a tow board
Largest diameter prop that will fit.
4-blade prop.
Low-pitch prop.
Your top-speed in the dinghy will be very low.
Get a longer fuel line, so you can move the fuel tank to the bow of the dinghy, to get weight forward.
Look at where the tow bridle attaches to the dinghy. If it’s too high, then the weight of the boarder will pitch the dinghy bow upward too far. So if that happens you’ll want to lower the tow bridle attachment points.
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To be honest, it’s all about the rider. I was very into wake-skating for many years. At the time, I was 6’3” and 215 pounds. Sometimes we used the first Yamaha PWC ever made, the WaveRunner 500, which only had 32 horsepower. Add the fact that the driver was my size, and that wake-skates have almost zero float when standing, and it made getting up extremely technical at first.
I thought I was really good at getting up, but I didn’t realize I had terrible technique. I could hold the ski in place under full throttle if I wanted to. Later, I learned to minimize drag and wait until I was completely on the surface before standing up. The longer you can stay low, the better. The more slowly you can bring your board up to the surface, like an airplane wing underwater, the better.
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I have a takacat and we learned to foil towing behind it with a 9.9HP engine. Both of us are around 170 lbs.
You want 15 or 20HP.
Bro. All these guys are tripping, you will be chilling on the 9.9. Guranteed I ride smaller foils and smaller boards. I’ve done it so can you, if theres something that everyone’s got right its that bigger board mo bettah
If you want to go out in wind or waves (you do), or with more than 1 guy on the boat, you definitely want 15hp and ideally 20.
There’s not really a weight difference between 9.9, 15, and 20hp motors if you go with tohatsu.
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