Hydro Junkie

You really have a choice.
1) You can use what I do which is a piece of MDF or particle board screwed to a pair of 2X2s after being cut to width. I like to be roughly 1/16" narrower than the planned width of the tunnel of the boat. I also have supports fastened to the inside of the 2X2s so that I can clamp the boat down without having to find something else to support the jig. I leave this flat so that I don't have to work around a raised area
2) You can take some MDF or plywood and cut it to match the bottom profile and attach two pieces to the top of that. The tricky part with this is you have to make sure the jig and bottom profile are an exact match or you could end up with a twisted hull. Since Mike's kits are tongue and slot, you shouldn't have too much of that to worry about.

Hydro Junkie

Time to resurrect this thread again. After several months of not working on the Pak, I'm back at it, along with a new "big sister", a 1978 Miss Madison gas scale. I'll see about posting pictures in the next couple of days.

crapshooter

love to see the gas scale hydro.

Hydro Junkie

Crapshooter, it's still under construction, just like the nitro scale Pak. I'll post a shot or two tomorrow of how far I've gotten.
One thing to be aware of is I've had to totally redesign the gas scale due to the frame spacing and correcting errors I found when I got measurements off the full sized Pak at the HARM
What I discovered is Roger drew plans for another similar boat and adapted them to make the Pak. This is most evident in the location of the firewall, which is too far aft, and the airtraps behind the sponsons, which are actually drawn more like on the 1974 Valu Mart.
I've corrected both of these issues on the gas scale during my redesigning and will be fixing these issues as best I can on the nitro scale

Hydro Junkie

Okay, now that it's been almost four months, I figure it's time for an update.
Between work and other "required" activities, the boats have had very little done on them. The Pak now has both nontrips, the side panels aft of the sponson transoms, installed. I've also started to rework the air traps and sponson bottoms to match the full sized boat's left sponson. I could not use the right sponson's measurements since it was replaced after an accident in Mexico in 1981 with a different design made from fiberglass so using it isn't an option. To take it one step further, when Ron Jones replaced the right sponson, he made it four inches wider than the left, mostly for aerodynamic reasons.
As for the gas Madison, I've epoxied in the engine bay walls and the relocated firewall. The engine bay walls have been modified to their actual appearance as I've removed the plywood where the flashpans will go and have started laying out where to glue the plywood that will make the flash pans. This will be a modification I'll be making on the Pak as well since I've layed out where the firewall will be going and now have a general idea where the flash pans will go. The part that makes the flash pans difficult is that they are twisted. The front of the pans have a flat bottom, the rear is twisted to 45 degrees due to the depth of the pan's inboard edge as the bottom is almost parallel with the bottom of the boat.

ob nut

My Feedback: (1)

If ya take off those dancing shoes , you might find time to complete these more important projects!!

Hydro Junkie

DUDE, IT'S NOT DANCING SHOES, IT'S WESTERN BOOTS AND DON'T YOU FORGET IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Actually, the boats get to take priority over other projects starting in October. Got the Elam repaired, only to oversleep and miss the race on Sunday so I get to put it on the shelf for the rest of the winter. That means the builds FINALLY get the attention they've not gotten all summer, that is if my work schedule allows it

ob nut

My Feedback: (1)

My bad...

Hydro Junkie

BTW Mark, the wife and I still owe you a lunch though, unfortunately, it probably won't happen for a few years, that is unless you come out west

Hydro Junkie

After several months of not getting to touch any of my boat builds, I finally have gotten time to work on the Pak.
Today's task has been to start reworking the sponson bottoms to look more like the full sized boat's left sponson. Since the right sponson is not original to the boat and is wider than what was originally on the boat, I'm not trying to copy it's shape or look.

Hydro Junkie

And, once again, work shuts me down. I did manage to get the sponson insides cut down to scale depth so they at least will look right. Now, when I get the chance, I get to make a pair of doublers for the sponson insides so that I can correct the size of the airtraps as well as make them the correct thickness. The plans call for 1/16" thick airtraps when they are supposed to be 1/8". On the full sized boat, the airtraps are actually 1" thick. I now also get to start reworking the sponson frames to get the shape of the sponson bottoms correct. That said, I'm so glad I did all of this rework on the gas Madison while resizing and cutting out the parts

Hydro Junkie

Okay, time for an unpictured update. Was working on the Pak over the holiday weekend and found several things that are going to be difficult, at best, to correct. One is the thickness of the sponson insides. The biggest issue is that, to make the airtraps the correct thickness, I'll have to laminate a piece of 1/16 ply to the inside of the airtraps. While this wouldn't seem that hard, and it's not if the boat wasn't half built, the plywood already in the build has a slight bow in it that, even if laminated, will still cause issues. I guess this leaves me three options:
1) Try to laminate a piece of ply to the entire sponson inside and hope I can flatten it out
2) Laminate pieces of ply to sections of the sponson inside and hope I can flatten it out
3) Start from scratch using 1/8" ply to begin with
Anyone have any thoughts on this? Just in case I do start from scratch, I went out yesterday and spent OVER $75 FOR TWO PIECES OF 1/8" PLY!!!!!!!!!!!!!!!!!!!!!!!!!!!
I figure that, if I do start over, I can fix all the errors I've come across by, once again, redesigning so I don't have to hack into what's already built and possibly make the boat too weak to survive the pounding it will take when racing

crapshooter

How many carrots of gold are in those ply pieces you paid $75 for. i really think you might be better off using the 1/8 th ply on the sponsons rather than trying to laminate and fix any warpage issues.

Hydro Junkie

That's what happens when you buy from a LHS these days. I'd rather buy from him, though, that to have him go out of business. There's only three hobby shops left in my area and, of the three, only the one is a full service, if there is such a thing anymore. One is basically a car shop with an outside dirt track, the other is a train shop with a few plastic models, neither one is really worth stopping at for building materials.

Hydro Junkie

And finally, time for an up date. Between work and the wife, along with redrawing the sponson insides to make a Pak with "correct" sponsons, I haven't had the chance to do much on the boats. Did a bit of laying out of corrections on the right sponson framing and found I'm going to have to add doublers on almost every frame due to lack of material to do the frame bottoms properly. Once I get the doublers completed , I'll post some pictures of the two sponsons with the different layouts so you can all see how much difference there is between the plan design and actual scale sponsons

Hydro Junkie

I guess it's time, after almost two years, to get back to this thread. Work has been a real time killer, even through the work shut down back in March and April. Prior to that, it was 12 hour days or nights that ended up being cut back to 9, even during the shutdown as I was considered necessary personel. By the time you add a commute of at least an hour each way, I've been looking at days of 11-13 hours.
Now getting back to the boat, I have managed to get the sponson insides cut out and am now working on redrawing the cross frames. Needless to say, with the Hydroplane and Raceboat Museum being closed until at least mid October, it's slowed me down since I can't make any research runs down to get information off the boat. Hopefully, I'll be able to post a few pictures this weekend with some updated information as well