Getting my Dink to Plane

[chris95040]

I've got a hard v-bottom inflatable, 8.5 ft, with a 6hp outboard. At the beginning of the season when she's got zero growth and it's just me alone she'll plane and get going really fast, engine roaring to life. Any more folks or growth and the party's over.

I've seen dinks with trim tabs on the transom, and I've seen big wings attached to an outboard's anti cavitation plate, curious if anyone has had success with any of these.

I'm guessing they help a little but not enough to get my dink planing with 2 people....

[Jim Cate]

Yes, the fins on the outboard lower unit do help somewhat... depends upon the specific boat. Another thing to try is a smaller/lower pitch prop. This will let the engine get up near its horsepower peak when loaded down, and can make a big difference IME.

Keeping the bottom clean, perhaps using antifouling paint, is always a good deal.

Cheers,

Jim

[MarkJ]

Dolphin wings on the OB are the best $45 you will ever spend. But a 6hp ob will not plane with 2 lard-asses. Mine is an 18 hp and that rockets, where my old 9.9 would only rocket with me alone and a clean hull... It would plane with a skinny girl attached, but not after a pasta dinner.

[CarinaPDX]

I have an AB 260, also a RIB of that size. I bought a 15hp Merc at the same time. The 2-strokes were the same basic design from 6hp (73#) to 15hp (75#) so I went for the 15 and am very glad I did. Even with that much power 3 adults is the limit for planing. I did add Doelfins, which help keep the nose down while trying to get up on a plane, and make the ride a bit more stable while up on a plane. I would recommend looking at the one-piece designs like the Stingray instead of the two separate fins of the Doelfins.

When buying a planing dink it is important to remember that longer lengths plane easier, and of course weight is the enemy. So get the longest that will fit your situation, and the lightest that meets your needs. Your 6hp on a 10' inflatable floor dinghy should have no problem planing with 2. Just a thought for next time.

Greg

[lancelot9898]

For a number of years I had a 5hp Nissan on a 10 ft Archilles with the wood floor and was able to plane with myself (200 lbs and wife at 120). It took some effort with weight adjusted forward as much as possible, but once on plane I was able to back off the throtte. I did have Nissan send another prop since the standard prop was not able to plane the boat and if memory serves me correctly the new prop did have a higher pitch rather than lower. With that higher pitch, it took longer to achieve the necessary speed to plane the boat whereas the lower pitch just didn't give enough speed to reach plane.

[Blue Stocking]

Originally Posted by MarkJ

Dolphin wings on the OB are the best $45 you will ever spend. But a 6hp ob will not plane with 2 lard-asses. Mine is an 18 hp and that rockets, where my old 9.9 would only rocket with me alone and a clean hull... It would plane with a skinny girl attached, but not after a pasta dinner.

I admire the scientist in you

Please post a photo of the girl Ah c'mon, don't be greedy.

Dolphin wings work well.

[chris95040]

Alright I'm sold on trying something. Looks like the fins are a cheap ($40ish) thing to try, but has anyone tried lifters attached to their transom?

Www.maxi-marine.com has them for about $120. They are like static trim tabs. Looks like you end up with a lot more surface area, might really help when towing w/ motor attached....

But maybe the dolphin fins, being right above the prop, are still more effective....?????

[Terra Nova]

Your outboard is too small.

[a64pilot]

The dolphin fins help hold the bow down is about all, trim tabs do the same. It's more efficient to lean forward or position as much weight as possible in the bow until it gets on plane though.

Jim's point is best though, if your not propped right then that will make more difference than anything.

[zeehag]

doel fins are great, but for 2 people on plane in your dink-- buy a 9.8 or larger outboard, as size matters in planing.

[over40pirate]

You know the solution. 15 HP !!!
I had a number of inflatable boats, soft bottoms and ribs. 1.2 hp (Curse and Carry) 6, 9.9, and 15 HP.
The 15 weighs the same as the 9.9.
The 15 allows planeing with more people and gear.
Lets you get on a plane, then back off until you are just on a plane, where there will be less wear on the motor, and get best mpg.
I hate having to run a motor wide open, where if I had a little more power, I could use 3/4 throttle or less.

15 HP also give you more power for when you have to do the following:

More power to pull a halyard from the mashead, to get the keel off the bottom. (Your boat or someone else aground)

With the dink tied alongside, 15 hp will move the boat faster than a 6 HP, when trying to get across the Gulf Stream, with no wind and the diesel quits.

Gets you and mate, with provisions, back to the boat as fast as possible, when it starts raining.

Lets you explore further from your boat.

When you get older, a outboard crane to lower/raise the motor works great.
The last place to throw your back out is on a boat!
Been there done that. While solo! Talk about scary.

[magicmoments]

Please keep us informed, I have your exact problem,

Mine will plan with 2 if the stars align, but only then, so close but so far. I even tried high test gas.

My Evinrude 6 Hp weighs 54 lbs, I tried a friend's Merc 9.9 but the weight had the back of the dink too low, but it was scary fast. If only I could get a 8hp 2 stroke

[MarkSF]

Originally Posted by magicmoments

If only I could get a 8hp 2 stroke

You can, that's what I have. Yamaha 8SF. I bought it as a 6hp, but put on an 8hp carb and exhaust pipe. Those are the only differences apart from badging.

You have to be careful when buying an older outboard though, mine had been neglected by the PO, and ended up needing a new cylinder block. He had concealed the extensive corrosion between the engine block and the lower unit, by assembling them with a large quantity of car body filler. What a s**t.

Oh well it's great now and gets my Zodiac 300 RIB onto plane easily (I am 280 lb) and then you can back off on the throttle quite a bit.

[nimblemotors]

What you need is a bottle of nitrous oxide.
That will boost its power for a few seconds to get on plane.

[MarkSF]

That would be cool, just like in the Mad Max movies. Question : will nitrous get my 11000 lb sailboat with inboard diesel on plane?