SeaWeedEater

I have been reading the posts on RCU for quite a while. I have finally finished enough of my other projects to persuade my wife into letting me take on another one.

Soooo….Here I go!

I started this project about two weeks ago. I wanted to build a gas boat from scratch. Anyone can go out and buy a RTR or for that matter a Kit. I wanted more of a challenge. I wanted to build as many of the components as I could with the resources I have available.


Power Plant-
I will be using a 25cc Homelite trimmer engine for power. I haven’t made any modifications to the motor. I want to install it bone stock and then start modifying to see how much improvement each modification provides.


Hull Design-
After searching the web for free boat plans I came across Powerpete's cracker box plans. I liked the cracker box design but it wasn't exactly what I was looking for. I read tons of posts on RCU and various websites and here is what I gathered on Hull design.

Deep Vs - Stable, look good, great for rough water. However, the V hull must constantly split the surface of the water increasing drag and decreasing speed.
Cracker box - Skips across the water like a rock. Enough Said. Note: I have had the pleasure of driving a full scale Cracker Box with a Chevy 350. I've never been so scared in my life this thing was FAST and my kidneys still hurt from the bouncing.
Hydroplane - Very fast and very unstable in rough water.
Catamaran - Fast, stable, but not very good in rough water.

My decision.... Use a little of the design features from each.
Deep V – Fore ward to cut the big waves.
Cracker box - Flat bottom at the transom to get the hull up out of the water.
Hydro & Cat - Install a thick keel and two keelsons to allow the hull to ride on when at full speed.

The first picture is what I came up with: Note: I didn't include the keel and keelsons on the drawing.

As you can probably see the design is loosely based on a cracker box. I shortened the length to 48” with a beam of 15”. The superstructure (Cockpit) is based on that of a Deep V. I added more tumblehome (inward slant) to the transom to give the design some class.


Building Materials-

I have been working with wood since I was big enough to swing a hammer. I have built several full size boats. My preferred building method is that of Cedar strip planking. Considering that I have loads of 1/4 X 3/4 X 8' Cedar strips I wanted to adapt that building method to my RC boat. I cut the bulkheads out of ¼” Birch plywood. Mounted them to a ¼ sheet of ¾” MDF and started planking the hull.

This is where I’m at now. I have the hull planked and started to Bondo the imperfections. Since I will be fiber galssing and painting the hull the bondo won’t show. Please excuse the fuzziness of the pics. I took them at 6:00 this morning before the fog lifted.

I’ll be posting the progress and pore Pics as I Complete the project.

So let me know what you think!

Oh Yeah! I believe that you shouldn’t get paid for what you love to do. Then you can’t call it love anymore. So I have the plans in DWG, DXF, and PDF if anyone is interested I will be more than happy to e-mail them to you.

Aaronie

Looks like a cool boat. [8D] Good job! Looks like a cut down WHH Sport hull. Keep us updated!

Aaron

pompebled

That's a cool looking hull!

Are you going for subsurface or surfacepiercing drive?

I'm building a deep vee at the moment, slightly longer (52"), also to be powered by a 25cc Homelite.(pics in my gallery)

Keep us up to date on your building progress.

Regards, Jan.

OLD_SLOW and in the WAY

I am gonna take this hull and resize it to 49" and make a rule stretcher crackerbox out of it. to look much like the black drawing you posted


[link=http://p086.ezboard.com/fjimsrcboatdockfrm2.showMessage?topicID=3191.topic]Same idea.....click here *[/link]

w00tw00t

im building one just like that at the moment! same pwoerplant, same hull design. cool

ernest2

hey cool boat!!! very nice design.. but i guess you can't run it fast in big waves.. can you post some pics showing the frames, before planking. i am about to start to start making a boat too, though its only 35" long.
thanks!!
ernest

skoda450

I too, have the do-it my-self bug. I currently have two boats, scratch built from my own designs. One deep V and a IMPBA legal Cracker Box. The deep V is 53" long 14" max beam, 24deg dead rise with an "Enforcer" style deck, power is from a McCulloch 32cc Homelite style (cantilevered crank) engine. The Cracker Box is 46" long with 19" max beam, 0 deg dead rise with a 25cc Homelite for power. Both are original designs and made from 1/8" plywood "stitch and glue" assembled from flat panels and glassed on the inside and out. I have a freeware program that lays out the full size panels for hard chine boats. They are both finished with a final gel coat outer finish. Getting the gel coat to look right as a finish without paint was a painful learning experience. All other hardware, stuffing box, rudder, surface drive prop support are also hand made. The prop, shaft bearing, drive dog and engine are the only commercially purchased components. I would post pics but my connection is too slow to upload them.

w00tw00t

ernest, ill post pics of mine... as its still mostly open

SeaWeedEater

Thanks for the replies to my post!

ernest2
I don't have any pictures of the bulkheads before I started planking. I can tell you that I drew a center line down the 1/4 sheet of MDF and then drew a perpindicular line where each bulkhead was to be placed. I then glued 1"X 1"X5" blocks of cedar along each bulkhead line where it intersected the centerline. From there I attached the stations to these blocks.

Now for the Drive System

I also wanted to construct as much of the drive system as I possibly could.

I have decided to use sheet aluminium and UHMW plastic for the strut. UHMW is an extremely tough plastic that is used in industrial jigs and fixtures. I will be drilling a 1/4" hole through the UHMW and inserting the drive shaft direcly into the UHMW. From there I will use a break press to bend the sheet metal to form sort of an angle and then run a bolt through both of the angles and UHMW. I know this sounds confusing so I will attach some drawings below will help explan the concept.

As for the rudders I will be using a dual rudder system that has two mounting bosses one on either side of the strut. These bosses will be the same aluminium sheet / UHMW laminate used for the strut. Directly below the bosses I will place the trim tabs with a bolt threaded through the boss to adjust the angle of the trim tabs.

The first Pic below is the same aspect as the other drawing but this one has the drive system drawn in. Yes I'm going to radius the top of the strut. I think it looks cool.

The second drawing is a larger aerial of the transom. The square at the end of the shaft is a quick representation of the prop.

The third drawing is a side profile of the rudder boss. This is a crude drawing but it represents the bolt going through the boss and pressing down on the trim tab. I don't see a need to attach the bolt to the trim tab in order to pull the trim tab up as the force of the water should force the tab upwards to the bolt.

The beauty of this system "If it works" is that I will have a total of $15 tied up in the rudders, strut, and trim tabs. I will need to purchase the prop and drive dog.

Man! That was a lot of information in a few short lines of text. As I complete the drive I will be posting pictures to hopefully reduce the confusion.

Let me know what you think.

Has anyone ever tried using UHMW as a strut before?

Hurrijeff

Hey SeaWeed...

Your doing great so far. Sounds like your plans will work. I just wanted to suggest that you run your prop shaft out the back of the boat instead of under it. By putting it out the transom you'll make things much easier on yourself and improve the performance of the boat. Try to extend the shaft beyond the back of the boat about 2 1/2 inches and make the angle parallel with the bottom of the boat. The set back will insure that your prop gets good water during your hole shot and the elevation of the prop will reduce drag once you plane out. Make the exit point for the shaft at the very bottom of the trandom, right where a drain plug would be. ALso your going to want your rudders to be slightly behind the propeller. There are a number of reasons .. pressure waves , deflection etc. but the main reason is that the prop needs "clean" water at all times.

As part of the trim and tweaking process later.. you might find yourself actually pointing the prop up a few degrees.


Good luck ! Have fun ! Keep us posted !!!

skoda450

After looking at the design and reading your "combination deep v and cracker box" hull I have a concern for you to consider. A flat hull doesn't want to change direction as there is no side resistance in the water for the rudder to push against. Cracker box hulls need a turn fin at the CG to turn the hull. Your design has deep v in the front but once you get up on plane the rear has no vee to turn the hull. You may want to put a turn fin just behind the last of the front vee section.

ernest2

hey thanks!!! it's great that your making most of hte hardwares.. i will too, but not much maybe, i don't have the necessary tools to do so.. anyway, i'll be making 2 copies of the frames so that i can make 2 similar boats.. 1 i will put 2 jet drives and the other the prop drive(in case my jet experiment doenst work)..
where's the pics wootwoot??
thanks!!
ernest

w00tw00t

theyre comming. im tied up with work but i iwll get some up. i kinda just "made" them one day.

weldman87

My Feedback: (21)

I was wondering if you could please tell me wher to find thr plans for power petes cracker box boat. If possible please post a link. am looking to build a boat next winter. I have 2 used weed eater motors with a clutch on them. Thanks for the help.

spdde1

was wondering if anyone made motor mounts for a weedeater 25cc motor into a Panther 40" hull

Zac Price

This is great, I really like watching progress of a non store bought boat. If I may make a sugestion. The leading edge of the rudder really needs to be on the pivit point (so when the rudder moves, the leading edge doesn't) This will help the boats attitude.

gazza25

I have just purchased a wipper snipper boat 93 cm and i would like some help in propelers and how i go about making a cowling for it and if i do will it effect the motor

skoda450

gazza25 - What size is the motor? By my conversion the boat is 36 in long. Thats not much boat for a convereted gas motor. Need more data about the boat and drive set-up. What is the hull configuration? Is the prop under the boat or surface drive out the bottom of the transom. Is the motor air or water cooled?

gazza25

the prop is under the boao and looks like it is on a flexible shaft. The boat is a mono i think

skoda450

Need information on the motor size and cooling.

Joe Petro

My Feedback: (1)

I have plans in DXF format on my [link=http://www.ibuildrc.com/mono.htm]Site[/link].
These images and drawings were compiled from Jim's (www.jrcbd.com).
Plans for both the 46 inch and 48 inch version are here.




Joe Petro

Joe Petro

My Feedback: (1)

OK, the pic didn't work.

[link=http://www.ibuildrc.com/mono5.jpg]Link to pic...[/link]


Joe Petro

Captain Ramius

Looks good!


Beer helps with the drivers attitude.