Speedy sponsons

[Carruthers]

11B42A79-355B-434E-9C8E-0780D8774D77.jpeg Here is a newly constructed sponson of a c hydro that will see the water this summer

[Albert]

From what I've read on this forum in the deep dark corners tells me that a flat bottom is a worth 1mph, a good prop is worth 1mph, a nice crisp edge at the back of the tunnel and sponsons is worth 1mph. In addition to that a worked lower unit is worth 1mph.Painting a boat red may or may not be worth 1mph? Eating a light breakfast instead of a bagel may or may not be worth 1mph but that fancy carbon paint on the bottom definitely is a worth 1mph.

So the question is are these steps worth 2mph?

[ZUL8TR]

Not when aired out and sponsons clear of the water, no water drag there. The design advantage seems to be pointed to the turns when C hydros usually have some sponson tapping, but 2mph faster or quicker around the buoys needs to be tested and proven in a race with 11 others? Before and after gains for this sponson design may not ever be known. They do look good and excellent wood work.

The gains in speed are from the whole set up and a good driver. Once all is the best it can be in boat and engine the prop is Mr. Thrust and pitch + rpm to swing it = speed.

[Albert]

So do the steps offer more of less of a performance advantage than a bagel?

[Carruthers]

The steps do indeed offer the advantage of overcoming the weight disadvantage of multiple bagel intake

[modsquad]

[modracer7b]

I tried round sponsons on a "A" hydro back in the 90's and the problem that came out was that the front had less stability in the turns due to less flat on the sponson. The idea was to eliminated any sponson digging when they touched down and that part worked, but the lack of stability was a handful. I did not persue the design further after trying to work with it for a season and the boat became a nationals bonfire one year. Your design is in between what I did and the normal sponson, so you may have more success than I did. The boat I worked with also had other experimental design factors built into it which may have also affected the stability, so I cannot positively blame the sponson design for the handling issue.

[Carruthers]

These sponsons are flat in every way possible the steps help do that and eliminate the drag of rounding the pad down to the tip and the two chine angles just make it possible to achieve more angle without the weight disadvantage of a wide sponson while creating a lifting strake at the same time

[Entler]

Now do any of you all know why seagulls are called seagulls????




because if they lived by the bay, they’d be called baygulls!
just wanted to shed history and enlightenment on bagel technology

[Albert]

Semi serious question...bagels aside. If someone wanted to test the performance of such a thing and had a boat that was the same specs minus the stepped sponsons how would one do it?
I know on top of the boat you could employ the string and tape method to see air flow. But measuring drag on the underside of a sponson while cornering seems tough to quantify.

[ZUL8TR]

About as difficult as unscrambling an egg and getting it back in the shell as untouched! In a turn there are so many variables to isolate as fixed to determine the difference of how one particular variable changes is the problem. In a straight-a-way no problem sponsons are aired out no water drag if rig set up right. Hard to get 2 boats exactly the same even without the sponson difference. They are close to getting boats the same in Japan boat racing with Yamato engines. See link on how exact they build the engines on page 235 (scroll down) and for the boats on bottom of page 235 left click for page 236 (scroll down)

https://www.flickr.com/photos/fotois/page235

A look see at Boat racing in Japan

https://www.youtube.com/watch?v=Xqn5nuRkAxM

[Albert]

Maybe it’s a physiological advantage. “I believe it’s fast therefore I’m fast”.


I’ve read up on boat race it’s interesting just like a lot of things in Japan.

[ZUL8TR]

Head thoughts and Butt dino are subjective measures that are present

[Carruthers]

I like use use the spoon and a knife as an easy comparison on how water reacts to surfaces hold the underside of a spoon up to your kitchen tap and it will be sucked in hold a knife to the same stream of water and it will bounce off it is nearly impossible to compare the two in a racing situation but at the end of the day would you rather be a spoon or a knife

[Albert]

Modracer,
Is this like the dirt track guys turning the wheels right to make the car go left .

[modracer7b]

In a race, the most important number is the lap time. In the end, the guy that runs the lap in the least amount of time is the winner. That is why the fastest guy does not always win.

[ZUL8TR]

Yes Fast Lap time wins IF you get a great start position and do not get stuck in the really bad water back in the pack. Been in both places and bad water is not good even with good lap time. If I had the position I would clip the lead buoy in the turn to force the guy behind to cross the wake if they were taking the inside. Of course without cutting off and violating the distance rule.

[Carruthers]

I don’t know about you modracer but I usually like to use my skid fin to do the work as it’s intended and keep my sponsons from being an anchor

[modracer7b]

Fins don't always get you around fastest either. I have used skid fins, bottom edge fins, retractable fins (when they were legal), center and offset fins on runabouts, chine fins, transom fins and at times no fins. I have some experience with what a fin will and will not do. Your air traps also work as part of your turning system. I was one of the first to use hydrobout fins for flat turning runabouts. I won a national outside chining a runabout with no fins, simply using the outside edge of the bottom and went from last to first around the outside of the other eleven roll up boats in the first turn. My point is that in some water conditions your sponson will be an anchor no matter what you do. If it is rough enough, the sponson will touch down and grab as will the entire outside of the boat.

[Mini Max]

Knife spoon, and cup. Tunnel boats may have a hook forward to plant in a turn. Have you seen a snow ski? Narrow in the waist and wide in the tips and tail for carving a turn. Just rolling your ankles will make a turn. Maybe that and a dollar gets a cup of coffee.

Me, I would look to venting the back of the sponsors as you would be dragging two big low pressure bubbles. I have seen a big yacht with 4,000 hp unable to get on plane because a solid swim platform had supports that end plated the transom. 4 " vent holes through the platform relived the vacuum and the boat took off.

[Carruthers]

I don’t believe one should rely on sponson suction to slow one down to turn that’s what the throttle is for keep the sponsons hanging as long as possible and when they do come down why not have them skip rather than suck as for the ventilated sponsons and possible transom I love the idea but did I not read somewhere that it is not aloud?

[modracer7b]

Don't get me wrong, I think your sponson design has excellent potential to work well. I just think you are anticipating an improvement in a range that is not there to get. There are and have been many different sponson designs and many different fin setups over the past 70 years and if one was that much better than any other everyone would be using only that one.

[Carruthers]

We’ll there is a significant amount of work involved in building these steps rather than the usual you see I enjoy it so that’s what I like to do but others may not agree but it is in no way my idea to do this I got the design from my uncle who is in the cbf hall of fame for his boat building over the years and all his outboards he built along with all his inboards had these sponsons along with all the unlimited boats that currently run so all I can say is I’m going to continue to have fun building these crazy steps and hopefully see success