RRR Tide Hydro - To Facet or Not to Facet?

[Otis]

To Facet, or Not to Facet, that is the question.

Hey guys, I was working on my 24" RRR Tide Hydro tonight, and was trying to decide if I should go with faceted or flat bottom sponsons.

When Andy K. put this design to paper back in '93, he laid out two options for the sponson profile. One has a wide, flat bottom, the other has a more anglular (faceted) profile with 2 additonal surfaces. The overall width of the sponson is the same for both versions, but the faceted version will have less surface touching the water.

Since this is my first wood kit, I'm considering doing the flat bottom version (lower parts count, fewer glue joints to screw up) ... but I'd love to hear the opinions of the group.

[B.K. Foster]

The question posed is whether you want the most speed you can get from the hull. If you want to go fast then keep the surface area that comes in contact with the water down to a minimum. Depending on wet surface area, you might not gain that much of a speed advantage. I think that guys like Dick or Andy will know more about getting the most out of your hull. But basic hydrodynamic theory will follow the rules of resistance and surface area. Even if you were to go with a flat surface on your sponsons, you could make up for it by a larger motor and higher cell count. The outriggers run quick and most of the boat is out of the water, but the flat bottom of the sponsons give it lift when getting on plane. It might be the same with your boat as well.

[Doug Forrester]

Otis
I think your thinking is definitely on the right track. Build the simpler, flat pad version. It will definitely be the easier build (possibly lighter, too) and that is recommended at this point in your building experience. There are a lot of complex factors at work here and the potential of a smaller wetted area of facetted sponsons does not automatically guarantee faster performance. Go for simplicity.

[AndyKunz]

The flat version has the wrong dihedral angle for any real performance. I designed it that way so my wife could drive it as a 22" boat.

Go with the faceted version. It will work well with Speed 700 power (it's extremely similar to the UL design - the UL canoes were built off 24" Tide plans!) and it handles high power quite nicely - nice enough for Doug Twaits JR to beat Dick Crowe at the Nationals with it.

Andy

[B.K. Foster]

Ouch Andy, that hurt all the way down here in the land of boots, hats, and scared water mocassins.

[Otis]

Faceted it is. Thanks guys! :)