30" Scratch Built Cat

[Jesse J]

Lomdel, I fully understand how that stupid wood can get the best of ya. However, you must conquer this beast. You had such a great thing going, are you sure you can't salvage the framing? I thought you were on to something really good. what happened? Oh well, I know people who got so frustrated they started smashing and then gave the fireplace a nice snack! I am sure you'll be back, there ain't nuttin like seein the fruit of your heart and soul and CA encrusted fingers go skitterin across the pond!

Kudos Norman! I am really psyched to see your creation make roost!

[lomdel]

Jesse. I am actually sitting at the PC tweaking the design as we speak. I am in negotiations with the laser cutting guy ( laser@mailbox.co.za ) to re-cut the frame out of 3mm Ply for me. I am also seriously considering shrinking the cat a bit to about 28". I will then try and run two 540 9L motors off my existing 3S lipos through X442 props. This is to keep costs down.
The main problem I have with the sheeting is cutting the profile of the sponsons out of the balsa after glueing a piece of 1/32" balsa to the frame. Maybe I should test fit it, trace out the profile, cut, and THEN glue...
I can speak of CA encrusted fingers! My wife hates it, LOL!

[Jesse J]

test fit, yep, thats what I do. I get a pretty close measurement (you are doing cross grain on the bottom and sides, right? parallel to the steps? good) and then fine tune the shape once I get the bottom and sides sheeted. It is the epitome of trial and error.

Why shrink the size? I have a 27" version and it screams on one motor.

ps get some sleeeeep, eh?

[Norman2]

Hi Jesse, I am in agreement with you and hope lomodel does not give up on his
project. I was going to paint today but the sun is not cooperating, Still waiting for
all parts from OSE and then wil post some photos. regards
Norman

[Norman2]

Hi Jesse and lomodel. Was able to get some finishing done. Still waiting for my
OSE stuff. Will continue later on servo. radio. and battery velcros. Regards
Norman

[lomdel]

She is beautiful Norm!! Please post some pics of underside and back as well. What does she weigh as empty as that?
I removed all the @#$%^ sheeting from my frame, cleaned her up, strengthened some crucial members and is now ready to re-sheet her. I will do the bottom of the sponsons and then apply a thinned (with what?) coat of resin to the entire frame and bottom before sheeting the rest. I am back on track and motivated...

[Jesse J]

Excellent Lomdel! Glad to hear it.
I use regular rubbing alcohol - someone please correct me if there is something better.

Norman, I am really curious to see how that inline strudder looks/performs. Got myself one for my 27" scratch built.

[Norman2]

Hi all. Jesse is correct. You can also use acetone to thin the resin. The hull weighs 15 oz. without
the hatch and canopy which I still have not received from tower. Will post some pictures this
afternoon. Regards
Norman

[Jesse J]

Wow, I just notice your pic of the finished product, very nice job! Could you post some more angles of you masterwork? How did the bottom come out? I am sure slicker than snot on a glass doorknob. I want to see her rear end too, maybe once you get your strudder in. I forgot, what motor you gonna slap in there?

[Norman2]

Hi, attached photos of bottom and transom. Regards
Noman

[lomdel]

Norm, some members here on OSE recently expressed their concerns about balsa's structural integrity. Do you have confidence in your build's structural rigidity and strength?
If I have to sum up the proposed steps of strengthening and finishing the hull it would go like this, please comment and correct me if I'm wrong:
Strengthen framework with thinned resin mix before sheeting. After sheeting with 1mm Balsa (cross-grain where possible), apply (spray or brush?) several coats (3x enough?) of sandable polyurethane sealer sanding (grit?) between each. Then apply a thinned resin mix (brush?) to outside for strength and sand smooth. Then spray primer and sand. Then spray final coat and clear coat(?). I am new to automotive finishing and would appreciate some info on this...

[Simon.O.]

Norm, some members here on OSE recently expressed their concerns about balsa's structural integrity. Do you have confidence in your build's structural rigidity and strength?

I have a lot of confidence in Norm's build as I do in my own.
I'll be watching his and I am sure he will be watching my build and development.
If used in the correct way as far as grain direction, thickness, and design. I believe that balsa has a place in FE despite some views to the contrary.
I will agree with JT that weight is not an issue now that we have lipo and BL. I have a bit of ballast in one of my hydros on his recomendation to prove that.

I use balsa with wads of good varnish as it is a lot less expensive than precision ply. I do use hardwood in a lot of places that I believe need the bracing or outright strength (transom).

Keep it going Norm and Jesse. The balsa boats will survive, if we make them tough enough.

[Norman2]

Hi, If you build them right then no problem,
Norman

[lomdel]

Hi, If you build them right then no problem,
Norman

I don't exactly know about the right way, but I am doing this one (more or less) my way.
I finished sheeting the sponson bottoms (with steps) and the sides tonight. She is beautiful!! I will take some pics tomorrow in sunlight.
Next I want to fibreglass/resin the interior completely for strength before I sheet the deck, bow and aft. BTW, I used 1mm balsa for the sheeting.
Be patient with my build, I have a baby and a 5 year old and a lot to do, so i burn the midnight oil on my projects...

[lomdel]

Here's a few pics of the sheeting up till now...

[Jesse J]

Yay, lookin good! I am really glad you stuck with it! I do think you might want to cross grain your sponsons with a layer of thin ply at this point. Even if you are going to glass it, a nice layer of 1/32" ply won't add much weight but will add lots of rigidity. Use some good contact cement and align the cross grain parallel with step.

whatcha gonna do fer a lid?

[lomdel]

Thanx Jesse. That (cross-grain the sponsons) is just what I am going to do next. Shouldn't it be parallel with the transom though? The decklid would be a simple ply sheeting on curved balsa beams resting on supports I glued to the inside of where the opening is going to be, but the cockpit will be glassfibre over foam shaped by hand. Still need to find a suitable foam though...
I received my stingers (Etti 4mm) and my rudder recently as well! Will post some mock-up pics soon. What is the rule of thumb for rudder behind prop distance? My rudder will be about 4cm behind the props. (Couldn't find a long enough short-standoff rudder...)

[OldMann]

Here's a few pics of the sheeting up till now...

Nice work. I give you some advice. Before you mount the top to hit with a lake for waterproofing. In this way, the lake will protect the wood and will not appear strains.

[Jesse J]

Nice work. I give you some advice. Before you mount the top to hit with a lake for waterproofing. In this way, the lake will protect the wood and will not appear strains.

Hi OldMann, could you clarify what you mean please? not sure what you are trying to say, thanks.

Lomdel, you can cross grain it however you wish. I was following the plans from Shockerman (the ones Norman used) and there it says to parallel the steps - and thinking about it, this way you have a nice edge at the back of your step and the curved part of the step is perpendicular to the grains, better deal, given your steps are slanted like yours are. Otherwise you could have potential for warping of the hull.

[lomdel]

Nice work. I give you some advice. Before you mount the top to hit with a lake for waterproofing. In this way, the lake will protect the wood and will not appear strains.

I also don't understand what you mean Oldmann .
Parallel to the steps it will be...

[OldMann]

I also don't understand what you mean Oldmann .
Parallel to the steps it will be...

Please excuse me if my expression is not correct. I live in Romania and do not speak English all the time

I said that before they mount the upper deck is better to waterproof the wood in order not to distort. Deformation occurs when the wood could be saturated with water. It may happen that in certain circumstances to enter the water in the boat, if not waterproof interior wood absorbs water.
Thanks for understanding

[Jesse J]

Ah, yes good point, waterproofing is a MUST I agree.

I have also noticed that the very act of waterproofing can distort the balsa. I had a nicely shaped hatch and went to polyurethane it and it went flat on me. lost all curvature and became rigid. So, yes waterproof before, but be ware that you might lose some curvature if you had it built in.

[lomdel]

I covered the whole interior of the boat with a coat of thinned fibreglass resin. The tunnel floor on the inside was covered with fibreglass clotch and regular fibreglass resin to provide a strng backbone for the hull. I will now cross-grain the exterior and apply a second coat of resin to the interior to make sure... Only then will I start the polyurethane sealer, sand, primer, sand, final coat and clear coat(?)...

[Norman2]

Hi Jesse an lomodel.
Some photos of some progress. Will now finish the canopy and post more photos.
Regards, Norman
Sorry will post photos again

[Norman2]

Trying to upload photos. Will try again tommorow

[Norman2]

Hoping the photos will upload. Wil finish canopy shortly.
Norman

[Jesse J]

that turned out real fine, good idea! can't wait to see her wet...

[lomdel]

That SV27 cockpit is a perfect fit! What are the length and width dimensions of the cockpit?

[Norman2]

That SV27 cockpit is a perfect fit! What are the length and width dimensions of the cockpit?

Hi lomodel. Your project is doing just fine and you are doing all the correct things
to make a strong durable hull. I will measure the cockpit today as soon as the
fiberglass resin dries. Don't give up. Regards
Norman

[lomdel]

Some pics of the cross-grain applied to the bottom of the sponsons. The sides will be vertically grained next. I also did a loose fit of the stingers and the rudder to see what it would look like. They were just put in place and nothing is set or fixed yet, obviously...
From a previous post you would recall that I applied a coat of thinned resin to the entire inside of the hull to seal and watertight. To make sure I will do another coat before adding flotation (pool-noodle) and sheeting the deck.