air trap

[tony Flakemore]

just started working on new boat Roger Newton plan 108 useing it for Notre Dame it shows a full length air trap for another style but not to use it for the Notre Dame as boat will be used for fun will is it better to use full length or not.

 

[Hydro Junkie]

I think it comes down to personal choise more than anything. I know I have a glass hull for the Miss Weisfields that doesn't have the air trap even though the full sized boat did for at least part of it's racing career. From what I can tell from pictures, the Notre Dame didn't have the air trap per se when it ran as the Spirit of Dayton Walters http://newtonmarine....850899471_RADAQ Roger drew one layout and one frame sheet and used it for all "like hull" plan sets later. I know the plan layout sheet shows the full length air trap while the color sheet shows the proper air trap for the 73 Pak

 

[tony Flakemore]

thanks for taking the time to ansewer Hydro if there is no real gain in running full length will build how original was built

 

[Hydro Junkie]

Part of the reason I'm thinking it's personal preference is that plan 108 was all earlier boats. When you consider that Roger did the color sheet for the 78 Madison in April of 78 and the 75 Technicolor/Valvoline/Bootheads in October 79, it's not surprising that the layout sheet had the full air trap. The hot engines back then were the K&B 67, OS and Picco 65s and maybe a few others. None had the power of the (now unavailable) Kalistatov(?), CMB or Mac 67s and therefore had to retain the air under the boat longer to provide the lift that the newer engines and newer hulls can produce without the airtraps.

 

[jwo]

The purpose of the airtrap is just that. It keeps the pocket of air underneath the hull. I sugest you build it with the airtrap in place. Run the boat and see how it reacts once you have it trimmed out. If you are having trouble with the back of the hull blowing up in the turns or kiting in the straights you can easily shorten them a little at a time to get the ride you want. It is much more difficult to add them later. The older Jones boats all add full length airtraps. They were a little deeper behind the sponsons than the rest of the afterplane. The rise in the trap just behind the sponson is there to dump air as not to get to much air in the rear of the hull. Moving the break a little forward also helps the models. John

 

[RodneyPierce]

I would also probably build them with the air traps in place. The hull might need it in order to get the back end out of the water without having to lower the strut excessively, causing the front recovery pads to be too close to the water. I would do as said above, and you can easily shorten them a little at a time if its trapping to much air.

 

[Hydro Junkie]

John, not all the boats had a full length air trap. The 73 Pak stopped at the break, as did the Weisfields, Redman and Notre Dame/Dayton Walther as seen by scrolling through the pictures at these links

http://newtonmarine....990562985_jpDCY

http://newtonmarine.smugmug.com/Hydroplanes/1980/11637073_HmAz7#990556286_DrHFX

http://newtonmarine.smugmug.com/Hydroplanes/1976/11501233_o4RMi#861845410_dERtD

Going back to my last post, here's a picture of my Steve Muck Weisfields hull bottom. You will see that there are no airtraps nor discernable bottom break and yet the hull was one of the fastest on the water for years

 

[jwo]

John, not all the boats had a full length air trap. The 73 Pak stopped at the break, as did the Weisfields, Redman and Notre Dame/Dayton Walther as seen by scrolling through the pictures at these links

http://newtonmarine....990562985_jpDCY

http://newtonmarine.smugmug.com/Hydroplanes/1980/11637073_HmAz7#990556286_DrHFX

http://newtonmarine.smugmug.com/Hydroplanes/1976/11501233_o4RMi#861845410_dERtD

Going back to my last post, here's a picture of my Steve Muck Weisfields hull bottom. You will see that there are no airtraps nor discernable bottom break and yet the hull was one of the fastest on the water for years

View attachment 29778

HJ Her is a picture that you might want to examin. These boats have full length airtraps. Your Muck hull has a Break at the sponson backs. Similar to the Velasco hull. Put a straight edge on the bottom and you will see it. The velasco hulls dont have airtraps on them either. With the break that far forward it is not crucial to have them. As I said before ALL the Early Jones hulls had them.

 

[Hydro Junkie]

You really need to look at pictures that you can see the whole side of the hull. I don't see an air trap on any of these at the transom

http://newtonmarine....990562985_jpDCY

http://newtonmarine....205884799_Jc3wv

http://newtonmarine....205884817_9Si5m

These three pictures of the Pak under construction clearly show the air traps stop long before the transom



Here's the bottom of my Muck hull. As you can see, there is no bottom break, rather a slow upward curve up to the bulnose from about midsponson

 

[jwo]

I stand corrected on the Pak. As for your muck hull that is called the break. The spot that the bottom moves away from the straight edge. Here is another picture for ya.

 

[tony Flakemore]

thanks for the extra info has helped alot thankyou