arcdude

Okay here's the idea, the lower diagram and I use that term loosely shows the center being foam and the dark lines are the lite ply and the red is the aircraft 1/8" ply that is countersunk into the foam, the bottom will be one layer and the top layer as shown has two layers glued together to provide 1/4" thickness for blind nuts and mounting strength and at the same time the center can be utilized as the radio box with a recessed flush lid. What do ya think?

1QwkSport2.5r

This is what I did to mount my engine stand to the my Outrigger hull. Aluminum L channel I epoxied and screwed into the hull ( to the liteply and balsa ) and then skinned over it. The pics are old and crappy, sorry.

Also, your sponsons are the about the same weight as mine.

arcdude

Now I see how you attached your rails, was curious about that. Where did your balance point end up being? Whether I go with the side method or the top and bottom will be greatly influenced by the type of mount I decide on and right now I'm kind of leaning toward a wood frame similar to an SI 3 for simplicity sake plus it's light and eliminates the need for a motor mount on top of it. Another major concern is the big honking motor I'm putting on this thing, if it were a 46 or something similar it would be much easier. I noticed the weight comparison as well however by design I created a much larger footprint in the hopes of not needing a launch ramp, in the end the smaller design may indeed be faster.

1QwkSport2.5r

I haven't finished the rigging on my rigger yet so I don't know how it will balance currently. Before with the old sponsons it would balance level by holding the engine stand aft of the engine itself (where the wood is in my engine mount). This is based on not moving the engine fore or aft. I will likely have to move the engine to get it to balance better now since the sponsons are SO different in their weight and location.

arcdude

Thanks guys for the suggestions however I can't use a side method because there is a curve to the sides as well as the top making it a bit of a challenge to utilize anything straight. So the final decision is to reinforce the top and deflect some of the stress's through the tub. What I have done is countersink one layer of 1/8" aircraft ply into the styrofoam which will be inside the finished sides of the tub and the second layer of 1/8" aircraft ply will sit on the top and be glued to the top of the sides. To complete the top of the tub lite ply will be used to complete the fore and aft sections which will overlap the lower layer of aircraft ply and butt up to the top layer and be cut out of the original top sheet and the end result will be a seamless top with adequate backing to bolt the motor stand to. The radio box has also been built into the top and the inside will be sheeted with lite ply which will act as bulkheads connecting the top to the bottom so that should also increase the overall strength. I had to use pieces to make the first layer of aircraft ply because I didn't have anything large enough and since it is completely glued to the top layer it won't matter in the end, have to make use of this stuff considering the price of it.

arcdude

the radio box is now cut out and a channel for the rudder control rod is grooved out and the control line is installed with a new piece of foam (blue strip) glued in the channel, the tube will only be glued at the radio box end so it may be removed or replaced at a later time should it be necessary. Once the radio box is shaped and glued in place the external sheeting can be done. The transom and rudder bracket are installed to determine where to install the control rod, and extreme caution needs to be exercised when using Gorilla glue due to it's expanding properties. I thought I was being cautious and ended up with glue coming out one of the blind nut holes and all I could do was pick it out for 1/2 hour with a pin until the threads were clean enough to thread the bolt in.

Jeremy_H

Duplicate

Jeremy_H

This is a big ol thing

If you get the glue in thread thing again, take a suitable bolt and put a hacksaw cut in the thread end, straight down the bolt. When facing the end file the left side of the bolt on each side, that forms a little tool that can be used to clean out threads if you don't have a tap to suit. Drill out the blocked thread with a drill that suits the core diameter (diameter of the bolt across the bottoms or root of the threads) first if you can.

arcdude

like a home made tap, good idea and I'll certainly keep it in mind the next time for sure. The glue oozed out for a whole day, not a pretty sight. Thanks

arcdude

What's a big ol thing, you mean the build?

Jeremy_H

Aye

arcdude

Okay, not too sure how to take that?

Jeremy_H

Sorry, I mean It's a large rigger. I've not seen anything bigger than say 2'6" overall, so to me that's a big boat of the type.

arcdude

Phew I was gonna put on my boxing gloves (kidding) but I did think you were talking about the size of the thread. The measurement of the tub transom to the tip of the front sponsons is 40" however the way I designed the rear I can make it any length I wish, you'll find out shortly. This is an experimental boat so the more versatile in adaptations the better.

Jeremy_H

My intrigue increases as you go along. I really hope this pans out for you.

What's your local sailing site like for such a thing? On our club pond the water prop riggers do OK, but with my SI3 it's like threading a needle at every turn at the moment. You know for a maritime nation we're pretty arse at boating facilities inland in the UK, especially here in the South West.

arcdude

I live two minutes from the Ottawa river which runs through the Capital so it's wide if I'm not mistaken 1/2 to 1 mile and goes on forever, unfortunately there is lots of current and generally a lot of wave activity. There is some bay type areas where it may be suitable to run, I'll have to hop in the canoe and check a few out when the time comes. That is why I built the boat with a little extra height from the waterline, maybe it'll help.

arcdude

Okay the next addition I added was a 1/16th support plate out of aircraft plywood and blind nuts on the sides of the rear by the transom to allow me to attach pretty much any creation I can come up with. The one idea I may attempt first is to extend the rear by about 6" out beyond the transom with light weight small sponson's (kind of a water born tail dragger), another idea is some form of foil that'll run on the surface. The reason for this is to lengthen the hull due to the overkill engine I'm using which is the ST 90 so there won't be a shortage of thrust to weight if the hull comes in under the 4.5-5 lbs expectation, so the extra length would be an asset.

arcdude

Here the sides have been glued onto the foam in the same fashion as the sponson's earlier, it was a little tricky to keep everything lined up so what I did was lay the foam on it's side and place the cloth over it and then put the glue onto the side panel and carefully line it up, basically in one shot without much movement before the cloth had a chance to snag and get messed up. Then I flipped it over and did the same to the other side and then laid it on it's bottom and placed clamps along the tub to snug everything together, a piece of 3/8"x3/4" spruce was used under the clamps so the pressure was evenly distributed.

arcdude

This is what it took to hold the bottom solid as the glue cured, that is about 65 lbs in the middle of the tub. The sub mount for the engine is ready to be glued on and as shown in the pic I did several lightening holes in the lower sheet as this will be completely covered by the top sheet so strength shouldn't be compromised and a small weight saving in the end.

Jeremy_H

Nice neat working there. I may have missed this, but are you glassing over the outside?

arcdude

Thanks, the intent is to glass the entire outside, any suggestions? everything I've ever built has been glassed over, it seems to work for me. Hope this doesn't become an anchor sometimes it's hard to estimate final weight when using a method you've never used before such as this ply over foam glass idea I've come up with.

arcdude

Here's the engine sub mount glued together and ready to go on the tub, the engine mount itself will be attached by 6 bolts to the blind nuts installed in the sub mount. Now that all internal work is done the rest of the exterior panels can go on and finally get a look at what I've created

Jeremy_H

There's only one little bit of advice I can give about glassing that kind of thing in case you don't know, which is use a squeegee. I've seem some folk applying with a brush, but that's no good for fine woven mats. It's a kind of glassing a surfboard technique, dry mat laid over, then pour through resin, squeegee out such that you don't pull the mat out of shape, and so that any excess resin is removed fully. remove too much resin and the mat will pop up over corners.

guess the best advice is to practice on something else first.

arcdude

Thanks Jeremy, actually I was eluding to other methods rather than glassing such as just epoxying the outer skin but I'm not too comfortable with methods I haven't done before. I'm well experienced in using fiberglass and typically use a credit card or something similar, but the squeegee idea sounds intriguing so I'll give it a try. One thing I've not encountered before is how to keep the gel out of blind nut holes, in all the items I've glassed it has never come up. One idea may be to wax or apply wax paper to a dowel or something that fits the hole snugly, I'm sure something will come up and likely last minute.

arcdude

Since it was such a nice afternoon I took the tub outside to complete sanding the edges down. I took a couple of pics while outside to get an idea how the little beasty is coming along and placed a 4' level in the background for reference, at least it'll help paint a more accurate picture. Next step is to make the nose pieces for the sponson's and the tub.