Dumas SK Daddle driveline

[dannyual767]

I posted this same question on another forum but there seems to be a lot more people on this one so I'm looking for more opinions/info.

I'm having a lot of fun building this "old school" Dumas boat. I own a real Sanger flatbottom v-drive dragboat with a big block Chevy and this SK Daddle is real similar! The instructions were done back in the 60's, as is the whole design of this boat, and the instructions suck. Thankfully, I've built Dumas boats before so that I could fill in the "gaps." The engine and driveline recommendations are real "old school." Actually, the straight shaft, angled driveline is very similar to my Sanger .

Anyway, I want to use a much more modern driveline like racers use for their fast monos. I'm planning on using a 3/16" or 1/4" flexcable vs the straight shaft. I'm going to buy some of that nice looking machined aluminum hardware and hang the prop several inches behind the transom instead of under it like the instructions have it. Now keep in mind, the bottom is flat. Real flat. I was thinking of having the cable exit the transom so that I could run a surfacing prop but I was told on another forum that I would experience way too much propwalk. A flexcable exiting the bottom of the boat with a submerged prop parallel to the bottom was recommended. I can do either. I'm just looking for some more advice before I install the engine and driveline.

BTW, the hull is 36" long and I've got several engines including OPS .65 and .67 as well as K&B .67 and .82. All of these may be a little too much for this boat but I've already got them so I'm going to put one of them to work in this thing! Thanks!

 

[Scott Schneider]

Man thats a blast from the past !!

I built one in the early 70's with an ENYA 60 and hard shaft drive.

Kept the boat in storage untill the late 80's when I got the bug again to play with RC boats.

Once I started to run it I found the drive to be real outdated and a real Pain In the Ass to maintain.

So I pulled stuffing tube and replaced with a 3/16" flex cable, yanked the rudder too.

Reset with a J&G combo strut / rudder assm mounted on the transon.

WHAT A DIFFERANCE !!! Sucker was a lot faster and turned better ~~ Well better for a flat bottom.

Set stuffing tube depth @ 5/8" to 3/4" deeper than keil depth.

Have fun and keep in mind it's only a play boat for super smooth water.

Scott

 

[dannyual767]

Thanks for the reply, Scott. Way back in the late 70's, when I was in high school, I remember seeing this boat in the Dumas catalog. Then, in 1986, I bought my full sized Sanger flatbottom dragboat. After many years, I got back into rc boating and about 2 1/2 years ago, I saw this SK boat on the Dumas website. I had to have it!

How far off the transom is your rudder? How far back is your prop? I know that this boat isn't going to turn like my Dumas DV20 or my Aeromarine Avenger and I know that it's going to need super smooth water, just like my Sanger does !

 

[Scott Schneider]

Have not had that boat now for over 10 years. But typical with that hardware the drive dog ends up @ 2 1/4" back and rudder @ 4" or so.

Once I realized how antiquated the hull was I sold it. Now some 25 boats later I really never miss it but still have the memories of seeing it skip like a stone at speed.

Owning a Sanger, I am sure your kindeys are not what they once were

Have Fun. Scott

 

[Flyin Rat Sass]

baisically any hardware that allows you to adjust the prop angle and depth will work.the hardware from prather for "7/5 cc inboards will work fine.

danny have a look at what i'm up to,taking the flat a little further with a fiberglass 43 inch runnerbottom

My Boat

AND HERES A PIC OF MY SK-Daddle

View attachment 2486

 

[Flyin Rat Sass]

and heres a pic of my scratch made out driveMy boat

 

[dannyual767]

That Sanger is one rough riding boat in anything over about 8" chop. 1 ft max !

I know the hull is antiquated but it'll be fun skipping across the water. Scott, did you use a skeg like the instructions recommend?

Flyin Rat Sass I love those boats . They look just like the real thing! How did that outdrive work out on your #357 boat? The hardware I was planning to use would put my prop about 4" behind the transom of my 36" long SK.

 

[Scott Schneider]

Yes it did have a center skeg made from .030 stainless.

Without the skeg it really won't turn!!!

B) Scott

 

[dannyual767]

That's what I was told on another forum as well. I'll get one from Marine Specialties for $9.50!

 

[rcboatlover]

Danny,

I'm working on the same project as you! I started building it this winter and should have it done in two weeks. Just like you, I diden't like the idea of using a solid drive line and went with a 3/16" flex shaft and a strut mounted on the back of the boat. I bought a Speed Master strut and rudder from Rocket City Racing for around $65.00 . It's some really nice hardware and should work well with the boat. I'm running the boat with a kinda rare O.S. .40 four stroke marine engine. I can't wait to hear it run!

I'm going to post some picts when it's done. I just need a muffler and alittle more paint work.

Keep us posted on your boat!

Dale P.

 

[Flyin Rat Sass]

Flyin Rat Sass I love those boats . They look just like the real thing! How did that outdrive work out on your #357 boat? The hardware I was planning to use would put my prop about 4" behind the transom of my 36" long SK.

i'm shure that would be fine hardware,one important thing to know about these hulls is that they need a little bit of a "rocker" built into them (the bottom of the hull from the transom to 4 or 5 tnches forward should have a slight curve [a 1/16 inch or so]upward,instead of flat or even worse down). this allows the boat attitude to be controlled by the trim tabs.if the hull is flat in this area it remains too "wet" with the bow planted,trim tabs too high and you can expect it to "air out"here's another pic of my hardware,made without any machine shop equipment, in my 2 bedroom apt (lol) it is kicking major butt in the bench racing circuit as I've been very busy with work and perfecting the glass hulls,you have no idea the kind of time and work it takes to get 43 inches of fiberglass to this point ,but i am doing it because i enjoy the learning process as much as the end result

View attachment 2490

 

[Flyin Rat Sass]

here's another shot of the hulls i'm developing (drag boat web sites being my main source of reference material)

View attachment 2491

 

[Kez]

Flyin,

How did you make that strut without any machine shop equipment? Can you share your secret? Did you use a band saw and a file? And how did you bore for the shaft bushings?

Regards,

Kez

 

[Flyin Rat Sass]

kez

I got it to this stage with a sawsall and carefull hacksawing then it was all flap disk sanding starting with 24 grit.I drilled and reamed the hole at the stage in the pic with drill press model #38119 from harbor freight ($40) the time spent was not economical until you figure in the experience and learning i gotted

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