Increasing the efficiency of Chine flats...

[Aquatek]

I had an idea that might increase the efficiency of the outboard chine flats on a fast planing hull.
The water that sprays horizontally off to the side of the flats contains a lot of kinetic energy that is simply being wasted and not utilised....In other words a lot of fuel is being wasted throwing water off to the side of the boat instead of being used to lift the hull out of the water to reduce drag and increase speed.
If the side panels of the boat could be extended downwards beyond the level of the outboard starboard and port chine flats then the water could be trapped under the flat for much longer, until it could exit at the transom, and hence more of its energy could be harnessed to help lift the hull out of the water.
This would of course result in reduced drag and fuel consumption.
It may be slightly more efficient for the inboard edge of the side rails to have a concave curve, so the water has to turn downwards to escape from under the chine flats, increasing the upthrust as a result.
If I'm right, this simple idea could save an awfull lot of fuel!

Any comments and suggestions would be welcome.

Regards

Aquatek.

[woodboat]

I believe your idea has merit. this seems similar.
http://www.thesmartrail.com/

[Aquatek]

Blimey, someone else had the same idea!....Almost exactly what I had imagined it should look like too!
Looks like I was right then, so I may incorporate the design into the 30'-40' fast planing hull boat I am planning to construct in the near future.

Thanks woodboat.

Regards

Aquatek

[lewisboats]

yeah...but $1200.00...Please! You are talking about $100.00 of aluminum here...talk about markup!

Steve

[tom28571]

This not a new idea. In fact it was used in the early part of the 20th century. It is shown in a photograph in Weston Farmer's book, From My Old Boatshop, and called a "wave Collector". There is very little in the shape of boat hulls that has not been tried by someone earlier. I have a pilothouse cruiser that I designed about 8 years ago that uses chine flats that are turned down transversely about 3 degrees. That is only part of their design, but I think it is effective. The purpose of the design was to get the boat up on plane quicker at low speed. The boat runs level at all speeds and gets up on plane at a lower speed than any other boat I have ever seen.

Nevertheless, Walt Shultz of Shannon Yachts,

http://www.shannonsrd.com/design.html ,

has been able to get a patent on what he calls the SRD (Shultz Reverse Deadrise) hull form and they are producing boats of this type.

If the patent is legal, I can only think that it is limited in scope and does not include the basic principle of negative deadrise near the chine of the bottom. Otherwise it just shows the lack of research going into patent applications.

Since My boat has been in the water for over 5 years, I think I am safe from them. After Hinkley's arrogance about "Picnic Boats" and "Southwesters", who knows what can happen?

I think it is a good thing to incorporate into your new boat but you should also look at how you plan to use your boat. The reversed chine can cause chine tripping in sharp turns if the boat has lots of power or is very fast. How much power or speed? I don't know, but greater deadrise aft in the main hull will lessen the potential problem, up to a point. If the boat will bank inward sufficiently on high speed turns, you will be all rignt but beware of a too flat transom bottom section with these down turned chines.

[JR-Shine]

What happens when you turn? Does the boat not trip on the edge.

[tom28571]

As I said in the last post, a downturned chine can indeed cause the boat to trip in turns but there are several factors involved. When a boat turns, the stern slides sideways away from the turn. If it's a V bottom, there will be a high pressure area on the outside half of the hull bottom and low pressure on the inside half. The flatter the hull, the less inward roll effect is seen and the boat just slides sideways. The propeller thrust acting below the stern also creates a moment to heel the boat inwards, especially on an outboard.

Round bottom boats actually may roll outwards in a turn, which is very disconcerting and, like a tripping chine, can be dangerous. This is caused by the negative pressure created by the convex surface sliding sideways.

More speed and/or power accentuates the tripping tendency. Very flat bottom boats need a non-tripping chine to avoid the problem. This is a small longitudinal section of the bottom at the chine that has positive deadrise to create the high pressure area mentioned earlier.

So, it's a combination of things working together (what else is new) that causes tripping, including weight distribution, especially passengers. This is not a complete story but it should get to some of the basics.

[Aquatek]

Originally Posted by tom28571

This not a new idea. In fact it was used in the early part of the 20th century. It is shown in a photograph in Weston Farmer's book, From My Old Boatshop, and called a "wave Collector". There is very little in the shape of boat hulls that has not been tried by someone earlier. I have a pilothouse cruiser that I designed about 8 years ago that uses chine flats that are turned down transversely about 3 degrees. That is only part of their design, but I think it is effective. The purpose of the design was to get the boat up on plane quicker at low speed. The boat runs level at all speeds and gets up on plane at a lower speed than any other boat I have ever seen.

Nevertheless, Walt Shultz of Shannon Yachts,

http://www.shannonsrd.com/design.html ,

has been able to get a patent on what he calls the SRD (Shultz Reverse Deadrise) hull form and they are producing boats of this type.

If the patent is legal, I can only think that it is limited in scope and does not include the basic principle of negative deadrise near the chine of the bottom. Otherwise it just shows the lack of research going into patent applications.

Since My boat has been in the water for over 5 years, I think I am safe from them. After Hinkley's arrogance about "Picnic Boats" and "Southwesters", who knows what can happen?

I think it is a good thing to incorporate into your new boat but you should also look at how you plan to use your boat. The reversed chine can cause chine tripping in sharp turns if the boat has lots of power or is very fast. How much power or speed? I don't know, but greater deadrise aft in the main hull will lessen the potential problem, up to a point. If the boat will bank inward sufficiently on high speed turns, you will be all rignt but beware of a too flat transom bottom section with these down turned chines.

LOL!...I cant believe it took him four years to create that!!!, when my design only took about 4 seconds!

BTW, I have already considered all of the potential problems with such a design and so I have designed a solution to prevent "tripping" during turns and one which makes it unnecessary to use negative deadrise aft hulls!
I'd like to tell you about it but I may want to patent it one day.

Regards

Aquatek

[tom28571]

I think patents are almost useless for an individual in the hullform field. Very few are specific enough to control getting around them with minor modifications. How many active patents are we aware of that actually limit what one can do with hullform. Not many, I suspect.

[brian eiland]

Check out Speed Rail(s) by Ocke Mannerfelt Design

[Aquatek]

Originally Posted by tom28571

I think patents are almost useless for an individual in the hullform field. Very few are specific enough to control getting around them with minor modifications. How many active patents are we aware of that actually limit what one can do with hullform. Not many, I suspect.

I think your right, and I could'nt afford to patent any of my ideas anyway!
So...here is a sketch showing my two designs:

http://sigmasd10.fotopic.net/p19566202.html

(Click on the pic to see it full size)

And no, it wont necessarily mean a wider beam hull as a result, because if my solutions are incorporated into the design from the start then beam sizes can be kept within the usual limitations.
Oh, and dont worry too much about the size of radii C) and D) as I am sure both can be reduced in practice.

Regards

Aquatek

[tom28571]

Aquatec,

It's good to save money on patent applications. Many thousands of boat with these features have been built as the very popular Boston Whaler. The concept for what is called the "cathedral hull" was patented by Dick Cole in 1959 (patent #186480). Ray Hunt is generally credited with the deep V and also used such chines on some boats. Without the central hull, it is also the same as Hickman's even earlier sea sleds after he found that they had trouble in turns and were hard to maneuver.

I have been humbled by a little research into boating design history several times when I thought an epifany of mine was original. I'm still holding onto one since I haven't found any previous similar applicaton.