DD Caddy Build

[huntridewrench]

So...I'm starting a new boat build, this time with a DD Caddy. Most of the DD car motor boats that I see look like much more of a budget attempt than what is normal seen with gearbox or AC boats, so I have an interest in finding what a DD car motor boat is capable of when built with planning, quality, and a reasonable budget. The build will consist of a 14ft Marty Bray new rivermaster, with quickslick at first. After running Potts and Flying Eagle for a while with both quickslick and polly, I haven't yet felt that polly was completely nessessary in my case. I wont rule out adding polly at a later date, but would rather have the handeling, water speed and less weight for this build. The rig will be stainless, built as lightweight as possible without compromising strength. Single front driver, double rear with a pancake cage. Dave Powell will be supplying the airfoil rudders and a 30 gal fuel tank. I'll be dumping the exhaust from long tube headers thru 3 inch flex and out a set of Innovative mufflers. The engine will be a Buddy Branch 514 roller motor, that will swinging a 74inch ngq prop at the 3 mark. This boat should weigh in around 1450 lbs complete, so an unloaded pwr to weight ratio of about 5 to 1. My goal is to have performance somewhere comparable to a 6 cyl aircraft, with a little extra weight. From past experience with a 472 DD caddy I have had I know that my operating expense will fairly economical with this setup. Since I run in areas with bridges, a gearbox boat will have me limited on cage clearance, and my 6 cyl AC boat has had me frustrated with oil and fuel expenses. Wish me luck!http://www.southernairboat.com/phpBB3/p ... &f=48#[img]

[kwanjangnihm]

huntridewrench,

What is the weight of the 14ft Marty Bray rivermaster hull & do you have the horsepower/torque specs for the branch motor?

Will be a very cool build to follow!

[huntridewrench]

Marty told me that his 14ft weighs in at 380 to 400 lbs. I didn't put my hull on a scale, but I know that me and a buddy can pick it up and hold it, and I'm not superman. Buddy Branch tells me that the cad motor will make about 630 lbs of torque at 2800 rpm. Proof will be in performance, but I do know that my fresh o540 with 9 to 1 pistons and a cam won't turn the same prop with as much pitch.

[BluByU2]

You will be very happy with your setup, and your fuel economy. Is that Swamphunter's engine, and prop? If so, I think he has a 76" NGQ. We usually run together in Hernando/Potts, and most of the time we come home with half a tank of gas. Just make sure your run 93 octane, and AV gas blend. Good luck with your build, and I'm sure you will be impressed with it's performance.

[John C]

looks like your gonna have an awesome rig. that boat should be impressive with that Buddy Branch DD roller motor. He built me a 520 about 10 years ago and that motor is still running STRONG today. just turn the key and go. good luck with your build.

[Olf Art]

Sounds great ...... keep the photos coming.

[Deano]

. . . My goal is to have performance somewhere comparable to a 6 cyl aircraft, with a little extra weight. From past experience with a 472 DD caddy I have had I know that my operating expense will fairly economical with this setup. . . . Wish me luck!

Gotta agree with BlueByU2; there's very little doubt you will impressed with how it performs. If I were going to build a new boat it would be eerily similar to what you describe, for very similar reasons. You should be able to comfortably tote a bigger load, longer than with the other comparable engine you referenced.

If I were to view anything differently than you are, it would be in reference to the poly. Granted, racing is not high on my list of endeavors anymore, but to, me the single biggest reason to not install it on the front side would be if there was a question about how seriously it would hamper the ability to run dry, or perform like it was over-powered. I don't believe either to be a justifiable concern with what you proposing. Maybe just me, but I've grown accustomed to not having bottom maintenance on the list of things that inevitably take away from available stick time.

In any case . . .
No luck required, having done your homework and having made such choices on the front side.

[swampfox]

. . . My goal is to have performance somewhere comparable to a 6 cyl aircraft, with a little extra weight. From past experience with a 472 DD caddy I have had I know that my operating expense will fairly economical with this setup. . . . Wish me luck!

Gotta agree with BlueByU2; there's very little doubt you will impressed with how it performs. If I were going to build a new boat it would be eerily similar to what you describe, for very similar reasons. You should be able to comfortably tote a bigger load, longer than with the other comparable engine you referenced.

If I were to view anything differently than you are, it would be in reference to the poly. Granted, racing is not high on my list of endeavors anymore, but to, me the single biggest reason to not install it on the front side would be if there was a question about how seriously it would hamper the ability to run dry, or perform like it was over-powered. I don't believe either to be a justifiable concern with what you proposing. Maybe just me, but I've grown accustomed to not having bottom maintenance on the list of things that inevitably take away from available stick time.

In any case . . .
No luck required, having done your homework and having made such choices on the front side.

[huntridewrench]

Deano, I've been mulling over the polly thing myself, but again my intent is to build a "sporty" caddy. Not necessarily to race, but as light and free as possible. I've had polly and quickslick on other boats and the slick bottom has held up well, but those boats were lighter. I figured if the quickslick wears of quickly I can always add polly later. Can't really take it off.

Blubyu, it is swamphunters power plant and prop, but I'm moving to a 74 inch in a medium hub since my cage is already built and I only allowed room for a 74. Before getting this engine and prop I was originally planning to use a 72 three blade ngh prop and 472 caddy I had, but swamphunters engine is much stronger. More pics to follow as I make progress.

[Olf Art]

I agree about the poly. I personally cringe at the thought of punching holes in a brand new hull. Whether you need poly or not has everything to do with how you use a boat ...... I just never hammered on my stuff hard enough to feel I needed more than say, Steelflex. If you do later you can always add it. I've seen poly on big Jon boats ...... they were owned by crabbers who spend a lot of time around oyster beds. It all has to do with how you intend to use it.

Lookin forward to hearing about your build.

[Comanche-pup]

Also the AREA that you hinted at Art. logs, oysters, and rocks make a big difference


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[sidejobs]

As far as quick slick vs poly on a properly built DD caddy. I've had both. On grass the slick bottom was nice , however on sand and rough shit the poly was better. The performance difference was minimal. If your boat is set up correctly and your engine is strong you'll see very lil difference.

[huntridewrench]

Thanks for the input guys. May have to end up adding the polly, but unfortunately I've just put three gallons of quickslick down on the new hull. The rig should be getting finished up towards the end of this week, and I'll be building my gauge panel in the next couple of days. Will be updating with pics.

[jimbo_jwc]

You will be very happy with your setup, and your fuel economy. Is that Swamphunter's engine, and prop? If so, I think he has a 76" NGQ. We usually run together in Hernando/Potts, and most of the time we come home with half a tank of gas. Just make sure your run 93 octane, and AV gas blend. Good luck with your build, and I'm sure you will be impressed with it's performance.

[Deano]

Jimbo, It would be to everyone's advantage (especially yours) if you started a new thread in the Prop Talk
forum with this question. You will get much more input and avoid unintentionally de-railing this build thread.

The short answer is you want more pitch, not diameter. See you over in Prop Talk.

[One Eyed Gator]

It is dang hard to drill 400 holes in a new hull,with that said.

If you go poly you can run 1/4" poly to be light and still have good protecting. I hand that on my DD caddy rivermaster, didn't last long in the gulf. If you ever plan to spend much time is the gulf, specially during the winter, I would recommend 5/16 or 3/8".

I don't have any experience with painted on stuff running, I do know poly has saved me from destroying a hull several times.

If got it put it on and run it. Always easy to pull the rigging and add it later if you change your mind.

[huntridewrench]

I've been busy with work, but managed to get my gauge panel built. I used all Faria marine gauges, oil pressure, water temp and amps. I managed to find a small tach the same size as the rest of my gauges. It only reads to 5k, and bit better than the giant 7k tachs I usually see on DD boats. After getting the prop dialed in and running the boat, I find that I don't watch the tach nearly as much as the more important gauges.

[Captcrawfish]

Sounds like your building another sweet rig. Keep up the good work and I'm still loving the my lil laser with pe90 been a great boat thanks bud and keep up the good work

[huntridewrench]

Thanks bud, glad to hear that boat is keeping you happy. I honestly regret selling it, she is a sweet running setup.

[huntridewrench]

Parts pile is growing!!

[SWAMPHUNTER45]

Them headers are sexy!

[Olf Art]

Them headers are sexy!

Yup, long tubes build torque. Nice stuff! Don't be upset when I tell you that a pair of big high quality mufflers will build even more. Those little 'bullet' mufflers some folks use choke an engine to death.

[One Eyed Gator]

Yep My caddy ran better (quite and more pitch) with 2.5" exhaust and real SS mufflers than it did 3" and bullets. With the 2.5 you could barely ear it running at an idle.
Even had 2.5" transom dumps that turned down and to the center of the boat.

[huntridewrench]

Those of you who saw gains with different mufflers, what style of header were you using? If anyone has a set of different style mufflers to hook up before my final assembly, I'd be curious to see if there is an actual rpm increase and how much.

[Olf Art]

Those of you who saw gains with different mufflers, what style of header were you using? If anyone has a set of different style mufflers to hook up before my final assembly, I'd be curious to see if there is an actual rpm increase and how much.

It wouldn't be an RPM increase, but an increase in the torque your engine makes. That's what turns a prop. With more torque you can run more pitch in the prop.