cyclops2

I have just glued up all the frame parts and measured out the covering area of the skins.
The boat is a Roger Newton 48" Miss Supertest III.
I used 5 mm for the everything 1/8" or less in thickness. 1/4" plywood where called for. The skins are 1/8" AA Poplar.
Framing weighs 3# 6 oz. Skins weigh 3# 6 oz. Complete wood hull, less gear & the water cooled Homelite 25 cc stock.

Hull should not exceed 7#, worst case of no lightening holes.
There are 5 more I have to build for people to run this summer at boat shows & at a "Adult Day Care Center for Seniors".

How heavy can I get with the stock Homey 25 cc and still have all the boats look good when running together ?

I really would like a best guess on how much weight I have to reduce or how much weight I can add to the finished wood hull at 6 1/2# to 7#.

Many thanks, Rich

martno1fan

Hi Rich i run a woody mono it weighs 18lb fully loaded with fuel,it scoots along niceley gets up on plane no probs so youre hydro should be no diff,in fact it should be faster once up on the plane i would think.The boat now belongs to my 11 yr old son and he loves it,any pics of your hulls?.almost forgot its powered by a 28 cc weedy engine,wa 167 walbro carb prather 280 prop.
[link]http://www.youtube.com/watch?v=6DkwfMavcqQ[/link]

cyclops2

Hi, martno1fan.
The boat looks great on the water. I will be happy if the hydro runs slower than yours. Nice lean & turn. Good driver ?

It takes about 4 hours to glue up a skeleton. 4 sets of gluing steps. I put 1/4" x 1/4" strips in all corners of wood. As I modified all slots on each piece of the 1 st framing, I went back and modded all the other hull pieces. I will have to take the belt sander to the curved chines to get them to meet the frame tips. Roger Newton made a great plan of this boat.
Butchering the slots for the 1 size of plywood was very easy and accurate just by eye.

martno1fan

Thanks the boat handles great my lad loves it,i still have a soft spot for it too as it was my first gas boat,ill be starting a rocket hydro soon from zippkits.Any chance of some pics of your progress so far ?.
Mart

cyclops2

I still shoot with a 35 mm. [:'(] Old habits die hard. I am lucky to have pictures of my family.

I will run off a roll soon as I want to send some pictures of the 60 kids boats to the Education Center.

Rich

Hydro Junkie

I'm curious, is 5mm a typo? If not, it seems the boat will be masively overweight

cyclops2

Hi Hydro.

No typo. The complete boat will weigh between 10.5# & 12.0# maximum.

martno1fan

I used 4 mm for my woody skins and its plenty light in fact i wouldnt want it lighter as some have had issues with the boat blowing off been too light.Poplar isnt a heavy wood either so im sure it will be as light as most similar hulls using thinner higher density ply.The zippkits boat weighs in at 14-16 lbs i think so your not far away if yours will weigh 10- 12 bare hull,once you put the goodies in there

cyclops2

WAAAHOOO.

Back to the RC transmitter starters and chokes.

Gentleman, start your engines...........

Where is a very stable, balance point on these boats ? I will load them down so blow overs are almost impossible.
What Octura propellor would be a reasonable starting point ? I am definately favoring a solid S S drive shaft & strut setup

Thanks for the information on the wood weight variations. I will not hole saw any holes into anything. A "Brick outhouse with a rooster tail". Just what I am trying to build.

Life is good, Rich.

martno1fan

Have a read of the manual for the zippkits boat,balance should be 1/2 to 1" behind the sponson transom for the rivvet and rocket .any further back and you will get a blow over.click hydros then go down to the manual link.
[link]http://www.zippkits.com/[/link]

cyclops2

I am impressed at Zipp.
SS or Aluminum.
I will mount a turn fin just behind the Sponson. That is where it is on a full sized hydro I crew for. The hull side is backed and braced with lumber to the main engine stringers with S S threaded rods that extend out of the side for the Fin. That makes the Fin removable for transporting or working on the boat at floor height.
I will start cutting up some S S sheet for the Fins. Zipps 2.5" X 5.5" .
1.....What are the dimensions for rudders in this size boat ?
2.... Pros and cons about center or offset rudder for people on buddy boxes who have never driven a RC boat ?

How much does all that shiney stuff on the rear of the boat add up to ? Brackets, rudder, strut, water pick up, etc. ?

I could not get the manual to download fast enough. Will try later.

Thanks for taking me under you wing, on getting these hydros in shape.

Rich

martno1fan

Rich you probably know as much if not more than me about hydros but i have done a lot of research on these lateley ,im just pointing you in the right direction i hope .It shouldnt matter where the rudder goes ive seen some on the right some left i wouldnt ever put one behind the prop wash on a surface or sub surface boat though.Zippkits have a hardware package for hydros for $64 free shipping in the USA,not sure what your budget is but if you are looking at a few boats maybe you could see if Joe will do you a deal on several sets of hardware ?ive allways found him more than helpfull.
Mart

cyclops2

I have no budget.
I do the building of the boats to keep me busy doing something I like in retirement. Seeing people have a great time with big smiles on their faces afterwards, is what keeps me going.

I will build the rudders and support tubes like I did on the PTB. 1/4" S S & brass with Rulon bearings & grease. I have a ton of 1/4" SS sealed bearings left over from the PTB. I will make up a thrust frame in the hull & use 1 of the flanged SS bearings. I can make a strut with a SS bearing in it at a friends shop.

Do you happen to know where the center of a submerged or surface piercing prop should line up when looking at the side view plans of the boat ?

I really over bought stuff for the Higgins boat. I can use all of it up and more on the hydros.

Ok. Only thing left is a prop & pitch size and a rudder size. I will give Tom at Octura a call tomorrow and get his advice.

Thanks for all the guidence on setting up these boats.

Wish we could meet and thank you in person.

Rich

Hydro Junkie

I still say you are going to be disappointed. I will say it again,
WEIGHT IS YOUR ENEMY SO BUILD THE BOATS AS LIGHT AS YOU POSSIBLY CAN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
YOU NEED LIGHTENING HOLES FOR HULL VENTILATION AND WATER DRAINAGE AS WATER WILL GET IN OR YOU WILL HAVE RUINED HULLS FROM WATER DAMAGE VERY QUICKLY
Stainless steel isn't needed on these boats, 6061 or 7075 aluminum are plenty strong and lighter, not to mention easier to work with as far as machining. A solid drive shaft will work fine, just start the shaft out at an angle that has the prop hub centered even with the bottom of the sponsons. Something you are also forgetting is that the boats will need to be fine tuned in balance after they are assembled. This means adding weight, normally in the nose. By building the boats heavy, they won't have the ability to carry much balancing weight in the nose without submarining. Also, even though these boats are not really being built for racing, from the description of what you plan on doing, they will be more like tug boats than hydros

martno1fan

Rich no need to thank me mate its good to see people helping others and to think ive helped you is thanks enough mate.I agree with hydro lighter the better but i dont think they will be tug boats .Solid steel shafts will work fine although not as fast etc but as your not racing them it wont matter.Just try to keep the angle to a minimum and it should run ok.

cyclops2

Thanks for the ZIPPKITS manual location!!!!!!!!!!

It is like having you on a "hot line"

I will toot ZIPPS horn loud & clear as a building guide. I realized that My Motto of " Better to be lucky than good. " rules again. The Miss Supertest I am building has a "Dropped sponson deck".
That completly elimanates the need to cut the stress relieving slot into the front deck area. It automaticly creates a stress relieving extra strip of decking.
I will stain and polyurathane coat everything, as i close up with the top deck strips.

These boats are actually getting to be a very enjoyable experience.
The manual states rudder depth. At least 2" below the bottom of the strut. I will do the 2.5".
" " " C O G location.
The troubleshooting chart on the last page, is the best thing since indoor toilets !!!!!


Rich

cyclops2

Hydro Junkie.

Thanks for the reminders. I do intend to control the weight VERY carefully by completly fiishing the boat up to the point where it floats with no top decking. Always do that.
I then start adding in parts in priorty sequence. That way I get total weight & the C O G perfect.
Then I close up the top decking.

If there Are anymore pitfalls please post them. Medicene is kicken in.

Rich Thanks.

Hydro Junkie

Another thing you are also forgetting is how flexible you need the skin to be. Using the 1/16th(1.5mm) for skin not only weighs less, it also bends easier, making the compound curves on the deck and sponson areas easier to sheet. Let me show you an example of what I mean. This is a rolled up piece of aircraft grade 1/16th birch plywood. Total size of the sheet is 60X60 inches. In it's rolled up state, it's 60X10 inches

cyclops2

You are right about the compound bending of plywood. By sheer "dumb luck" my boat has dropped sponsons.

Life is good when I get lucky.
Not 1 big piece. I will be doing 3 top pieces per each side. Long skinney, relative, pieces.

I have a lot of money tied up in each boat. Frame and skins cost me $ 25.00 per boat.

I am getting hung up with my 1/4" x 1/4" gusset strips at all plywod intersections. There is about 125 of them. The frame work is getting unbeliveably stiff as it dries with each new bunch of gusset strips.

cyclops2

You are right about me over doing the the Brass & SS steering and Drive line parts.
I have a friend with a Heli-arc & Mig shop. He will do the welding after I shape the parts.
I am still in that "sport scale" mindset. I will save weight. Aluminum stuffing box.

Edit
I can drop the thrust plate inside the hull. I have flanged SS 1/4" bearings that I can mount on each end of the stuffing tube with small OD Aluminum collars against them. Lock tite a piece of really small sleeve on the shaft if I get brave.

Hydro Junkie

Your strut is what is supposed to take the push from the prop, not the stuffing box or the engine. Alternating a couple of teflon and thin SS washers is, at most, all that is needed between the strut and the drive dog as an anti seize to prevent power losses

cyclops2

Thanks again for a simpler way of doing a problem.

I have 4 more batten strips to mount & then the skinning fun begins.

powerroller

HJ. Any good sources you have to share for mail order plywood ?

Hydro Junkie

not in the 60X60 size. Only place I know of is B&D International in Tacoma WA, UNLESS YOU HAVE AN ULTRALITE AIRCRAFT SUPPLY HOUSE AT A LOCAL AIRPORT. I have found that the hobby shop variety of ply costs more than double what the large sheets cost.

powerroller

Thanks......I did find a place called aircraftspruce.com The ultralight idea is one I will check on.