1/10 scale hydro sponson bottom issue

[rat350r]

Over the past off season I decided to build three versions of the same boat. U77 Miss Wahoo, U00 Maverick, and U12 Miss Bud. The boats are built from the same Garry Finley plans. All three boats came out right about the same weight at 6 Lbs 8 Ozs give or take an ounce or two. All boats have the same hardware and motors and speed controllers.

Over the past couple of weeks I have run the boats. Of the three two boats are able to run 7 laps full speed and finish with all electronics in the high 90 to low 100 degree temperatures. One boat the Miss Bud U12 no mater what I do to it at half speed it will lift the left sponson and blow over. All three boats have the same CG strut depth and angle and I have tried several props but the boat still blows over.

After watching you tube videos by Scott Meyers outlining building RC boats I decided to apply some of the techniques he uses when he builds a boat. I started looking at the bottom of the boat to see if it was straight. What I found was that the left sponson bottom was straight but the right sponson bottom has what looks like a rocking chair rocker built into it.

In an attempt to fix this I used West System epoxy mixed with their faring filler basically making epoxy body filler. I applied it to the bottom of the right sponson bottom. Once it cured I sanded the bottom flat and now both sponsons are flat and even.

I plan on testing the boat this weekend to see if this makes a difference. If not what do I try next?

[Panchothedog]

I am sorry I have no cure for you but am very interested in how this works out for you. I have a popeye hydro, a tfl molded glass hull and am having the same problem. Please post your progress. I have made other hydros go faster and even ride more stable by doing what you are looking to do but never thought that it could cause a boat to flip the way yours and mine are doing. I'll be watching and rooting for your success.

[Fluid]

It?s difficult to diagnose from afar, especially without video, but there could be several causes. A rocker in the sponson bottom can cause suction, sticking that sponson to the water allowing the other to fly off because it has more lift. Another cause could be the turn fin, if improperly aligned it can pull the right sponson down.

Is the CG the same for all boats? Do you set the strut with the boat resting on a flat surface so it is absolutely flat? ?Eyeballing? the strut setting may not be good enough. Have you tried offsetting the packs to the left to help hold the left sponson down?

As you?ve learned, even boats built by the same builder from the same plans can differ; many people do not realize that and expect every boat to run the same with the same setup.. Let us know how the hydro runs with the bottom mod.


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[JimClark]

no twist in the bottom of the boat?

[RandyatBBY]

Make sure that both ride pads are parallel to each other and the same profile. Copy the good sponson to the bad. If you are looking for degrees on the set up table 2.5 is good. If you need help (Just ask me) setting up and how to read it. I will come back later and post pictures and info.
some of my boats past and present