Blackout

Should be a nice little motor. I love O.S., wish they still made front exhaust engines....

Hydro Junkie

You and me both, would be easier than trying to work around a 180* header when mounting the engine

Hydro Junkie

Passed another hurdle yesterday in the build, I RECEIVED MY ENGINE!!!!!!!!!!!!!!!!!!!!!
I was thinking the OS .18 would be close in size to the Novarossi 21s going in some other builds but no, it's not even close. Just for fun, I took a picture of the OS .18, the NR .21 and a OS .46 VX. I was amazed at how close the 21 and 46 are in size. Now I just need to get an exhaust system and then it's back to work. Here's the picture of the three engines listed above

Blackout

Yup, my NR .21 is allot bigger than my good old K&B .21's. Makes sense as the NR puts out way more hp....

Blackout

Does that O.S. 18 have a polymer cooling jacket??

Hydro Junkie

Yes it does, would rather have an aluminum one if they are available

Blackout

Wow, O.S. is getting cheap. A nice blue aluminum jacket would look much better. Though the correct polymer would probably get the job done. After carrying a Glock for 13 years, I'm a firm believer that the correct plastic can hold up to abuse.

Hydro Junkie

After a long delay, I finally got back to working on the boat. Todays task was to remove material from what is refered to as lightening holes. This step isn't shown in the instructions but is important for two reasons:
1) It lightens the hull, making it easier for the little OS 18 I bought for this build to get the boat up on plane
2) It prevents water from pooling in one area of the hull with no way to get it out

Trapped water and dead receiver batteries were what doomed my first Pak build to the scrap heap. Water trapped inside the hull rotted the poor quality mahogany supplied in the kit, making the boat so fragile that it broke in half due to what should have been a minor scuffing on some rocks. I'll post updated pictures in a bit, since I'm working on parts for my other two Pak builds as well

Hydro Junkie

Picture Time!!!!!!!!!!!!!!!!!!!!!!
The first picture shows the hull dryfitted together from the back left corner. It pretty well shows how much material I removed from the frames. The second picture shows that the inside transom doubler was also lightened in a similar manner. Even without removing the bottom areas of the frames for re-profiling the bottom or the fillers left in the middle of the cross frames, the hull weighs in at 10.75 ounces. I figure that will drop by roughly 30% when the remaining excess material is removed. Just for a giggle or two, I compared it to one of my remanufactured race kit builds and, even though the race hull is missing frame 1 and 2 but does have the rear bottom installed, it weighs in at 10.35 ounces. It will be interesting to see how the hull weights compare as the builds go on

Just got to thinking, it would be easier to see how much wood was removed if I repost the picture from page 1

toyotatruckin

Any progress reports yet?

Hydro Junkie

Not yet, as I've got to build a jig for it this week and then it's back to work. One thing of note is that the sponson transom on the left sponson was drilled out with a lightening hole just like the internal framing. I did this because I'm going to be laminating a birch face on both sponson transoms as well as a birch doubler inside the right sponson. As with all hydros, weight is a factor in how well it will run when finished so this was a way to reduce the weight without reducing strength.

advanced builder

Looking good on the build HJ , Is that the hull your going to bring to Madison? I know you have more hulls than that. The .46 will put you in another class .Yes /no My one ole, buddy loved his pay&pac ran the paint off the bottom.

Hydro Junkie

It may be one that I bring but it won't be a Pak paint job. Since the wife claimed it, she says it has to be purple since she loves that color. I have a variation on that kit that will be definately going to Madison and, if all goes well, be on the water at a fun run in Sellersburg over the July 4th weekend. Since that one has some major reworking, I'm not posting any of that build for now as I don't want to confuse anyone. No .45/46 in any of them AB as the hulls are not large enough to handle the torque or the physical size of that big of engine, even though I have two OPS, two OS and a CMB I COULD drop in

amax

Lookin Good HJ,,, Keep It Up!!

advanced builder

Are you staying with the stock plywood on the top& sides. The Dumas ply is iffy. depending on your kit. Some of the newer kits have better ply. I thought. She looks light with your mods.

Hydro Junkie

I'll be using the kit supplied skin with the possible exception of the bottom. It all depends on if the bottom panels fit the new profile on if they are used or not. The internal framing is also all stock except for the sponson transom faces and skid fin doubler, which will be birch ply as well. Before I started hacking at the frames today, the framework weighed in at 10.75 ounces, so I'm going to be shaving up to an ounce or so out of it today as I've been removing the bottom of the frames for the new profile, though that is being offset by the addition of the forward bottom profile glue blocks along the inside of the sponsons. I'll post a picture of the framing later today

Hydro Junkie

After reading Advanced Builder's last post, I did some checking and found the long bottom panel that was cut to fit the original rear part of the hull will work for the front in the new profile. The shorter factory front panel, however will need to be replaced as it's too short to work in the rear. So far, that's the only panel I've found that will need to be replaced with this configuration. I'm hoping that the only other material I have to replace is used to make the wing

advanced builder

Looks like you got your mind set. GOOD Funny thing about building things can sit for months ,then you dive in. especially when the weather breaks Are you going with CA as to epoxy. epoxy is heavy. But stronger Just me on that one. CA can be a little brittle if you don't add a bevel with heavy CA Like a weld OK Get-er done.

Hydro Junkie

I agree on both your points:
CA is lite but brittle
Epoxy is strong but heavy
For both those reasons, I use CA for tacking or initial placement and use epoxy for the rest. It is also due to those reasons that I have mixed microballoons in with epoxy and use it as a surface filler on the mahogany where the grain is more open. This saves weight and still seals the material. I'm also making sure that the mahogany side that has the tighter grain is what will be visible on the outside as it won't take as much to seal the grain.
Last night, I did install the remaining glue blocks on the sponson insides and finished cutting the bottom off of the cross frames. At this point, it's build a jig of some sort and break out the epoxy. One thing that I don't like is what the directions said about a jig, "The model is build on a simple jig. Obtain a 7 5/8" x 27" flat board that is either at least 1 1/4" thick or shimmed at least 1 1/4" above your work bench. Cut down particle board shelving works very well and is pretty inexpensive. Cover the jig with wax paper or saran wrap." This leaves a lot to be desired and here are my reasons why:
1) You can never be sure if your building surface is flat using a piece of particle board by itself. It can bow slightly if it's not placed on a flat surface and DOES NOT come in a standard size of over 3/4" that I've seen
2) You can't clamp to particle board as it will smash and crumble if you hit the edge wrong
This now brings up the question of what is a better alternative? Particle board is fine as a work surface, but it needs to be braced. After cutting to width, I normally take the excess width and rip it in half. The two pieces are then screwed to either a 1X1 or 2X2 cut to the same length, making sure the boards are straight. I then screw the 1X1/2X2s to the bottom of the building surface, giving you a solid clamping surface underneith the particle board as well as a raised surface using the left over particle board as supports as in the picture below. What makes this even nicer is if you need a wider or longer building jig for a bigger boat, you can just cut a new top as needed. I wouldn't make the jig any less than 36" long for that very reason. If you have a boat you're working on with a belly pan, you can just screw a second layer on the top to match the configuration of the new hull.
While I have tended to use particle board in my jigs, you do have to use care when building on them. Particle board will swell if it gets wet. It also absorbs liquid like a sponge. For these reasons, when using any sort of glues in the boat, be sure to have the jig protected. The same applies to using MDF, protect it from glues and liquid. One thing that you should not use is plywood. Being a natural material, it tends to curl and can't be made totally flat, been there tried that[:@]

f16man

I build my jigs from clear kiln dried pine run thru my jointer , makes for a solid foundation, also made an adjustible aluminum jig for the simpler hulls.

Hydro Junkie

That works too, did you laminate the top or what?

advanced builder

Starting to look more like a boat. , moving right along. dig in. When the construction ends and goes to finishing,I tend to drag my feet. elbow grease. more elbow grease. but it's part of the hobby.

Hydro Junkie

AB, if you're looking at the boat, that one is the 99 Madison, not a Pak hull. I used that picture to show the building jig and how the boat should fit, fairly snug but not tight

R.J. West

Looks good so far.

Hydro Junkie

Let me guess, RJ, it's very different than what you would do