New Gas Scale Projects...Scratch Builds

[Tim Strange]

Hello All,

I am in the process of getting things together to start a couple of scratch builds. I have the Newton plans for the '77 Atlas Van Lines Blue Blaster (#123 7701) and the '74 U-95 Turbine (#124 7495) and have blown them up 20% for Gas Scale. The bulkheads have been cut out from 1/8" MDF to use as patterns so I can cut the ply on a router table. Sounds like an extra step, but I will be able to create exact duplicates for each side of the hull...plus I will certainly need to experiment with modifications to get that side exhaust engine to fit in there.

I will have plenty of questions...but I'll simply start with this...

AIRTRAPS A PLENTY!!! Looking at the plans, I can see that there is probably an overabundance of air getting trapped under the hull...Especially the U-95. The bottom break is all the way back at the bulkhead just in front of the transom and the sides extend almost all the way to the bottom of the sponsons.

Any suggestions on changes in this area on either hull?

Thanks, Tim

 

[Hydro Junkie]

Some words of warning:

1) Roger drew all of his plans by hand so they do have errors. Rather than cut out the parts exactly as drawn, cut them oversized so you can sand to fit. I've never had a boat go together as drawn and have found that, by doing this, it prevents you from having a lot of wasted time and material. After you are sure everything will fit, I would make templates for new parts and future builds in the manner you have already done.

2) If you're going to buy premade cowls or other FG parts, have them on hand BEFORE you get everything epoxied together It's much easier to modify the parts, as needed, while everything is still out in the open than it is to try to make FG parts fit after everything is epoxied together

 

[brad nichols]

Just buy a ML hull as they fit perfect!!!

Brad

 

[Hydro Junkie]

Brad, it's hard to experiment with and make changes to a kit since, if he tries something and doesn't like how it turns out, he still has to make new parts. This holds true for any kit, be it a ML, Dumas, Whip or any other on the market. It's also why I build from plans, I can adapt and change what I want along the way with the only cost being pencil lead and possibly tracing paper used to change what I didn't like.

 

[Mike Luszcz]

The ML Boatworks 7495 gas kit that John Olsen ran in the Pacific North West seemed to win Hi Points about every year he raced it. Just food for thought. Mike

 

[Tim Strange]

Hey Mike, that's my Coors Light in my avatar built from one of your kits. Please take no offense, I apparently just want to torture myself with the scratch build experience. I also have one of your 106 kits which does go together nicely...just switching gears to '70s pickle forks. You certainly have done a great service for us!

Hydro Junkie (Mark), part of my plan is to make a couple of cowlings that molds can be made from...there just aren't many available for Gas Scale at this time. Also, that is a good idea to cut the parts out oversize. However, I decided to cut the parts per the plan and then I can rapidly cut the areas that work for each piece with the router set-up...and then draw and cut the offending areas to my needs. As far as time and money go, it is a hobby so I am not on a set time frame. As a bonus...the MDF only cost $9 for a 4x8 sheet and I have a bunch of luan on hand. Yes, I am prepared to create a bunch of scrap...

 

[P THOMAS]

Tim more cowls sounds like a good plan for the gas scale class. It is a good idea to copy and paste all the bulkhead parts on cardboard use a centerline and check if all the frame slots line up properly.

 

[jeffaustin]

As far as wings watch Greg Hahns video in the how to form....very easy and very light....made many wings using his method....thanks Greg

 

[jeffaustin]

I am working with a fellow firefighter making cowls and such using vacuum pump and bags. Still in setup stage.

 

[scott williamson]

My 73 budweiser gas scale is 25% bigger than Newton plans ,the break point is about half way between the sponson backs and transom .I reduced the height of the airtrap sides which extend below the non trip angle, that helped calm it down as did an air dam at the front of the trap and about 50 bucks worth of lead.

I plan to build the 74 paynpak from the same plans but will put the break point at the back of the sponsons,although that creates a steep ramp to the front of the trap,im not sure what else you can do without changing the scale look.

 

[lohring]

My gas scale build is described in Scaling Up. More details are here. The hull is very different, but the loads should be similar. I needed to continually beef up the various parts, especially the sponson bottoms and turn fin.

Lohring Miller

 

[Tim Strange]

Thanks for the input...I really think that putting the break point at the back of the sponsons does create to sharp of an angle. This is the way my Coors Light is set up, and it seems to me that it would be beneficial to have the air trap moved back a bit to help lift the rear of the boat. The Coors Light just looks like it is running uphill and is very easy to blow over.

Anyway, I haven't cut any new pieces. I have redrawn five of the bulkheads for each hull so that rather that rather than having a left and right piece...they will be one piece. I think it will be easier to get things lined up correctly. Especially bulkhead 5, which is the back of the sponsons.

The first thing I plan to make is a simple center section for each hull (the area between the sponsons), so I can experiment with motor placement without the extra bulk of a complete hull. I will also have a base to work on the cowlings independent of the actual working hull.

Happy New Year, Tim

 

[wayne middlemiss]

I agree moving the air trap break point more rearwards along with reduced height to reduce the inward air flow without over doing it. Remember what I told you Scott by utilizing water ballast tanks , can be filled , can be drained at will.

 

[scott williamson]

I agree moving the air trap break point more rearwards along with reduced height to reduce the inward air flow without over doing it. Remember what I told you Scott by utilizing water ballast tanks , can be filled , can be drained at will.

Thats what the holes in the tips of the sponsons of my Aussie bud scale hydro are for Wayne, to add weight if needed,the break point further forward does give a bit more room under the deck at the front .I may make a separate mold for the airtrap with the break point further back if im not happy with how it runs.

 

[Tim Strange]

Made a bit of progress cutting out the patterns from my new bulkhead drawings. Things were moving along nicely until my bandsaw took a dump on me. Hopefully my scroll saw has enough left in it to finish the job. I did manage to get the ply cut roughly to size for each piece so I can cut them with the router table.

I rechecked the patterns, and it looks like some of the rear chine angles are different...seems to me that they all should be the same? The transom for one hull actually has different angles on each side.