Delta Pad Bottoms

[Specmar.Aus]

Hello Fellow Boaters and Designers.

Sorry about the first post,

Here is my second attempt.

We are looking for feed back on DELTA PAD BOTTOMS on Power Boats.

Over the last few years we have been able to improve the performance of nearly all our designs using this simple feature.

I am looking for Data that may help in this area as all our work has been trial and error so far.

I use Hullform an Australian Design Program and all the Drag results are so close its hard to see any real positives using it.

Does anyone else use this feature on their HULL’S?

Note all hulls built this way to date are ALLOY.

Cheers Specmar.Aus

[nevd]

Hello Specmar.aus

Most of the ski boat manufacturers and Haines Hunter and Haines Signature have used pad bottoms for over 20 years, but most are not delta shaped. Some of the US bass boats use delta shaped pads. All of the Savitsky based programs will allow drag calculations with the 0 deadrise pad - problem is determining ride height in water for each speed/load combination. I also understand that a deadrise approximation is very accurate when the chines are not running dry.

What size and speed and deadrise are your boats and what manufacturers use your design?

Regards,

nevd

[Specmar.Aus]

Specmar.Aus


Hello NEVD.

Thanks for your reply; we are the Specialty Marine Contractors USA Australian Agent,

Stephen Pollard is the designer for all the boats we sell kit set alloy boats for.

I have used the delta pad on my own designs for Centre Consoles 5 to 6 meters and sailing Catamarans from 12 to 15 metres for 12 years with excellent results and sea keeping abilities.

There is a range of transom deadrise’s: they are from 12 to 20 deg depending on the size and use of the hull.

Most have a target speed of 20-25 Knots however the present trend is to power these hulls with larger 4 / Strokes and higher speeds to say 25-35 Knots+.

All delta pads are of 0 deadrise and they have 2 ½ deg rise compared to the buttocks to the transom, to give a bow up attitude on the plane.

Stephen Pollard has used trial and error over many years for the delta pad width and length, he has also settled on the 2 ½ deg neg as standard as well.

I am also aware that many Australian boat builders including Haines Hunter and Haines Signature, Swift Craft and the bulk of the Ski Boat and Race Boat builders have pad bottoms for more than 20 year’s.

I have found that the public are not as well informed as you might think and most Pro Builders that approach us need some sort of data to back up this hull form.

This is why I trialed the hulls in Hullform to see if there were any striking differences.

The outcome so far has shown at sub 20 knots more drag (wetted surface I feel is what the program can see) and less drag as the speed approaches 40 knots.

You can view the entire range of hulls on PDF at www.specmar.com this is the website for Specialty Marine Contractors USA.

Once Again I welcome your input and interest in Delta Pad Bottoms.

Cheers Specmar.Aus E-Mail Specmar.Aus@bigpond.com

[nevd]

I have an associate who may be interested in your kit boats in Australia.

Do you have a list and prices of the ones available in Australia - particularly with delta pads?

Regards,

nevd

[Specmar.Aus]

Specmar.Aus


Hello NEVD.

Again thanks for your reply;

We have quoted several hulls to date and have a good hand full under construction as well as exported as kits.

I can E-Mail your Associate a price list in AUD$ within a few days as most files are
Re-nested to suit the Alloy plate sizes here.

We use ONE STEEL as the supplier / cutter however your Associate is free to use other suppliers and cutters if they wish. (Strict conditions apply)

Once Again I welcome your input and interest in Delta Pad Bottoms.

Cheers Specmar.Aus

E-Mail Specmar.Aus@bigpond.com

Po Box 1180 Hervey Bay QLD 4655 B / H 0427 322 463 Fax (07) 4125 8080