hydro sponson question

[3autility]

Since hydros have to have rounded sponsons, why can runabout have pointed bows, not rounded in some way? Just curious.

[bh/]

-many were, and some still are . Andy Hanson's 'duck-bills ' were dominant, as were Craig Crafts. Some say it is easier to build a square nose than a pointy one . I would guess there has not been a demonstrated issue with runabouts ?

[runabout333]

The nose on a runabout rides a little higher???

[Big Don]

Because all the runabouts would be too short and not meet the dimensions, therefore being illegal, if we made them round them?

[18W]

Because pre side fin boats, most convention runabouts were able to turn right without dire consequences?

[csh-2z]

The one instance of a 90 degree impact causing an injury, happened in a hydro. A hydro, unlike a runabout (in most cases) the only protection a driver has is the coaming. The runabout has a side to deflect the bow of a boat from piercing into the cockpit. I was initially against the rule because there is an extremely rare possibility of a 90 degree impact. If the angle of the impact is less than or greater than 90 degrees, the sponson would mostly deflect or glance off of the coaming reducing the possibility of spearing the cockpit. Unfortunately, even the radiused nose of a sponson could, at a 90 degree impact, still pierce a coaming because we have not, with this rule, reduced the area of impact or the Pounds per square inch (PSI) of force. Now, you just have a bigger hammer.

[Ram4x4]

Well, technically, the PSI is reduced, the larger the impact face area, the less PSI on the specific area involved for the same force appllied. Still, I'm less concerned with the sponson piercing the coaming than I am of the coaming just simply snapping off on impact. There's a lot of momentum in a 450+lb boat moving at any speed and the side walls of our cockpits are not heavily reinforced. I mean, if a 200ish lb driver can bust through it in a hard hook, a full boat at more than twice the weight is going to snap it right off in a dead on collision.

I'd say most collisions of that sort are most likely to happen in a turn when a leading boat spins and bares it's side to oncoming boats. Fortunately, the speeds there are less than full on down a straight, but they are still moving pretty decently. To compound the issue, if a boat spins, due to the direction we travel, the side exposed is the same side the driver leans out of, so there is even less coaming wall to protect the driver.

At best, I see the rounded sponson as a mitigater, but nothing that will prevent a boat from outright crashing through the side of another.

The question then, is are we looking to completely prevent another boat from passing through another, or to minimize it? A big difference in the two.

[csh-2z]

I think all we can expect is to minimize the possibility. I still believe also, that the round tip sponson still has a very small impact area. The points on the sponson tips before the rule were not sharp like a blade or spear. Think of a bowling ball, with about a 5" radius still only strikes the target on one tiny point. That's how they roll!

[Roskowski30h]

Just food for thought, would you rather somebody throw a dart at you or a tennis ball? The wider point (after the initial impact) more evenly distributes the force to more than one point

[modhydro]

Actually a pretty good analogy, except I think a tennis ball weights even more than a dart. If you want to compare impact and inertial forces, the mass needs to be the same.....

[csh-2z]

Tennis ball is not a very good description. More like a large ballpeen hammer. I do realize the rule, under the right circumstances, can make a difference. However, maybe you can help me with this, I'm curious why the MOD rule grandfathered out all boats built prior to the rule's inception. Seems to me the age of the boat should not have anything to do with it.

[Ram4x4]

That I agree with. Age of the boat should not matter. A sharp point on an old boat is as dangerous as one on a newer boat. Seems a bit counter intuitive to the intent of the rule.

[modhydro]

years ago several IOA members met where I work to do some testing. I build a guided drop rig that let a weighted sponson accelerate around 28 feet to a sample of various cockpit side constructions supported in a stand. unfortunately, the sponson tips wound up breaking before all the samples could be hit. I can tell you though without a doubt that the rounded tips didn't penetrate nearly as far as the traditional ones. We didn't get through all the various kevlar and carbon skins on the samples.

I will see if I can dig up any of the photos from the work we did. While I built the test rig to investigate this, the rule was implemented and it all became a moot point, but physics is physics. While at the instant of impact the point loading is infinite (division by zero) the rounded tips increase in area far quicker and disperse more energy.

Steve

[csh-2z]

I don't disagree with that at all. My point was more the rarity of the 90 degree collision

[Ram4x4]

Also a valid point (no pun intended). Also consider other types of collisions where the pointed end matters, such as possibly hitting the driver in the water.

I don't know for sure, but I believe Logan Sweeney's crash at Lock Haven a few years ago, he took a sponson tip right in the chest. If that is the case for sure, I can only imagine how worse things would have been had it been a very pointed one.

I think we all agree the rounded tip is better than a pointed one for any collision where they'd be a factor. It may not completely prevent damage or injury, but is certainly better in that case.

Not to derail this subject, but considering the rarity issue of specific factors, did you know that SNELL testing standards for helmets includes dual impacts to the same spot on the helmet? I read an article a while ago from a former SNELL big wig and he was at odds with their testing regimen. He felt that forcing manufacturers to build helmets to meet this standard was actually hindering helmet technology from progressing at a faster pace. He said the chances of hitting your helmet in the exact same location twice in one wreck was incredibly low. The issue, as he puts it, is that instead of forcing helmets to reduce G forces further and (as the newer standards and technology advanced), they were stuck at 300Gs as the magic number because helmets had to be made "harder" and less impact reducing in order to pass the dual impact.

I just thought that was an interesting article (and I did mention it here before as I questioned why we're "stuck" on SNELL ratings (and FAI and SFI). I say that only because it is becoming harder to find "legal" budget priced helmets due to the color selections available in them (SFI and FAI rated helmets are typically very expensive, more so than SNELL rated ones). Anyway, that's a whole other discussion...

[raceright]

Because the runabout guys did not want the rounded nose.