hull design
 

Anybody ever seen any kind of design like this on a boat. this was on a kneeboard i had many years ago and this thing would glide way easier and much further than any other plain flat surface kneeboard i had ever seen.
I've heard of sanding at a 45 angle, making strakes wider, Any real life success stories, besides steps?


https://cimg0.ibsrv.net/gimg/www.off...8a3a77fd22.jpg

the dimple thing is what makes golf balls travel further. its been used on sailboats before too.

never seen anything like that but ive had a design floating in my head for a few years now as well.....i need to get a small 14' rowboat and start modding it up! :D

On our model boats, particularly the outriggers and hydroplanes, we use a technique we call "crosshatching" on the sponson bottoms. We drag the bottom of the sponsons across a piece of 1000-1500 grit sandpaper on a flat surface, in both directions, on a 45DEG angle relative to the direction of travel. You really can't even feel it, other than it feels slicker than the gloss painted finish. It creates significant aeration of the wetted surface, but doesn't create any unwanted changes to hydrodynamic behavior. This can translate into several MPH and a smoother running boat. I have often wondered if it would do any good for full size boats.



Thanks. Brad.
(937)545-8991

I sanded the back 1/3 with 320 grit and a DA sander. Also went along all the strakes with Cabosil and sharpened them up as well as the stern. Maybe picked up .5 or 1MPH. Not worth the effort in my opinion. Its a lot of freaking work on your back.

There was a guy on here 5 years years ago that did a lot of bottom changes. He swore by increasing strake width. He added 1/2 to straked by applying some kind of fiberglass sheets so they went down 1/2 and about 3/4 wider.

I raced stand up jet skis in the past. When we got a new hull, we'd take 36 grit sandpaper to the bottom of it and rough it up, removing all the gloss. The more scratches etc the better. They would handle so much better.

Keith,

The difference between our full size boats and model boats is the massive disparity in displacement. These outrigger hydros don't displace hardly any water at all, as far as the hull is concerned. They are literally skipping across the surface, which is obviously not the case with our full size boats. We displace a tremendous amount of water, even on a really high plane. That's why increasing the ride width of the strakes works; it gets the hull up out of the water, allowing it to displace less as it moves across the water. That being said....

A DA sander won't create the "crosshatch" pattern that we get on our model boats, and I think it's kind of the key to why it works the way it does. I'd love to see a slow motion video of the water passing over (under?) the ride surface of the sponsons, showing the aerated film of microscopic bubbles these straight-line scratches introduce to the flow. I do know it works, as I've done and seen many before/after same day tests, and the difference is visible to the naked eye, radar gun and lap times. Whether it can translate and scale up to our full size boats is probably going to be left to speculation.

One could ask, "If it is of any real benefit, wouldn't the MFRs do it to the hull bottom before they join the top and bottom shells?" And I think the real answer is that, if they did, keeping them clean and pretty would be a nightmare, and people wouldn't like it, even if they gained a significant amount of speed or fuel economy from it. But I CAN tell you, from the several buddies I've got from model boating that have worked with unlimited and limited hydroplane racing teams, that it is a very common practice.

Thanks. Brad.
(937)545-8991

Ocean Pro used to make performance parts for the PWC market and ride plates were one of them. They used to have a textured finish from the factory. Similar to a 150 grit sand paper. When Ken was asked about the finish, he said it created many tiny bubbles under the plate. Thus allowing the boat to ride on air if you will.

Whether this is true or not, I do not know? I do know the ride plates are a nice mod over the stock one.

Need a shark skin pattern on that last 6' of running surface.

https://theconversation.com/fast-sui...n-records-7960