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Rib-275 less motor or more davit?


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I have a rib 275 (105 lb) and a tohatsu 9.8 hp motor (115 lb with fuel tank).   I hoped to hang it off my garhauer dd 6-1 davits, but it’s too much load in waves.  

I’m not really interested in an engine lift.  I’d hate to store the motor aboard.   I have an option to swap for a 6 hp Mercury which would weigh half as much as the 9.8 and can.  Or I can consider dd 6-2 or other davits.  Maybe I need bigger davits either way?

I’d hate to lose the power, I’d be happy to lose the weight.  Davits are pricy.  
 

Wisdom is appreciated.  

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Do Garhauer themselves say that the 6-1 are too weak? I would think that a ~300lb load that's evenly distributed across both davits (boat + motor + full tank located in the bow) would be within their capacity, especially if the davit mounts are robust.

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Incidentally, I see on the Garhauer website that founder Guido Gargiulo passed away in January at the age of 88. I've had a few interactions with Guido and he was always very patient and customer-focused.

Rest in peace, Guido. 

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Thanks Istream, I will discuss with Garhauer, but since I bent one, either the davit or prior owner’s install were not up to the job I assigned.  

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You can start by not keeping the fuel tank in the dinghy.  The full 3.1-gallon plastic tank the engine comes with of gas weighs 28 lb with the hose. The engine itself weigh 81.5 lb, but that is probably dry, so figure 85 lb or so.

You can also remove things like the anchor, pfds, flare, or anything else stowed in the bow locker.

A dinghy in davits needs to be secured so that it cannot move at all in any direction when you are underway. It may be dynamic loading rather than the static weight of your dinghy and outboard that are causing the problem. There is a discussion of this in a recent thread here on davits.

If the davits bent or otherwise failed when you were just lifting the dinghy, that's a different problem entirely.

The davits on my boat are very similar to the Garhaeur design, but the primary structural member is 1 1/2 or 2" pipe, not the 1" tubing of the DD 6-1. If yours is really 1" tubing, that strikes me as too lightly built for the dinghy and outboard you describe, but a lot depends on the mounting arrangement, whether or not there us a crossbar, etc.

My dinghy and outboard are fairly similar in type/weight to yours, and when lifting the dinghy, the davits flex a bit even with the much larger primary tubing I have.

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The rib was empty except for fuel and the motor, and oars.  But point taken on the 25-30 lbs of fuel tank.   They are indeed 1” tubes.  There is a cross bar.  
 

The davit bent underway in about four foot waves, which I call Lake Michigan moguls.  Random nasty things.  
 

No votes for smaller motor?   I’m calling Garhauer about my installation and options on Monday.  Other brands to consider?
 

 

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If the Davits are really that marginal then dropping some weight on the motor is really not going to help.  You're not going to get the safety factor you need to be confident.  What happens when the cover gets ripped off in a storm and it fills with water?

Better to just pull it up on deck upside down, or tow it behind. 

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1 hour ago, Scrambler said:

The rib was empty except for fuel and the motor, and oars.  But point taken on the 25-30 lbs of fuel tank.   They are indeed 1” tubes.  There is a cross bar.  
 

The davit bent underway in about four foot waves, which I call Lake Michigan moguls.  Random nasty things.  
 

No votes for smaller motor?   I’m calling Garhauer about my installation and options on Monday.  Other brands to consider?
 

 

You obviously want your tender to go fast, hence the big motor.

I get by with a 2.4m aluminium dinghy (63kg) and a Honda 2HP outboard (12kg). Dinghy doesn't plane but I don't find that to be an issue.

My davits are 25NB Sched 10 stainless pipe not that thin walled polished tube. Design load of 150kg per davit with a minimum 2X safety margin so unlikely to fail at less than 300kg  load per davit.

I didn't buy them I made them.

FKT

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51 minutes ago, Russell Brown said:

Could you please send me one of those 12kg 2 hp motors? Can't buy them here. 

??????

Standard Honda air cooled 2HP engine, thought they were available everywhere.

FKT

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Only 4 strokes here. Don't think there's a single 2 hp outboard for sale in this country. 2.5 4 strokes are big & heavy.

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I saw stacks of 2.3 hp Hondas in the PNW a couple of years ago, weight is listed as 13.6kg dry.

We have one as well, nice motor.

 

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2 hours ago, olaf hart said:

I saw stacks of 2.3 hp Hondas in the PNW a couple of years ago, weight is listed as 13.6kg dry.

We have one as well, nice motor.

 

Exactly, mine is the older 2HP model, I bought it new as I trust used outboards to the same extent as I truse used chainsaws, that is not at all.

Looks like I'm out a kg or so on the mass, I thought it was 12kg but close enough.

And they're 4 stroke. IIRC Dylan did a few reviews/hate sessions on the Honda oversights.

FKT

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My setup: Walker Bay SLR 270 @70lb(ish); 1988 Evinrude 15 2-stroke @75lb. Runs like a scalded cat and easy to lift and manage. It is a wet dink; my ex Takacat was a drier boat and took only an 8-hp 2-stroke to plane… the WB needed 9 but the 15 is what I happened to find.

9/15 tends to be the same engine with different tuning, btw

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11 hours ago, Russell Brown said:

Only 4 strokes here. Don't think there's a single 2 hp outboard for sale in this country. 2.5 4 strokes are big & heavy.

Both the Honda 2.3 (air cooled) and the Suzuki 2.5 (water cooled) are 4 strokes and both weight about 30 lbs. Both are widely available in WA state.

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I guess I wasn't aware that the Suzuki and Honda are 10 lbs lighter than the Yamaha 2.5. What I need is a tiny get-home motor for my new power cat. The 2-stroke 2 hp is so tiny and light and I wish I could buy one. My buddy has the Yamaha 2 but he won't let go of it.

I burned up a brand new Yamaha 2.5 getting the G-32 home from Alaska. It was spectacular with plastic parts dripping off the motor and a toxic cloud pouring into the cockpit. Yamaha gave me a new one as they couldn't blame it on me. I was taking very good care of it and was getting close to 50 mpg with it. one fifth of a gallon per hour at 5 knots. Had fun getting the boat the rest of the way home.

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2 hours ago, Russell Brown said:

I guess I wasn't aware that the Suzuki and Honda are 10 lbs lighter than the Yamaha 2.5. What I need is a tiny get-home motor for my new power cat. The 2-stroke 2 hp is so tiny and light and I wish I could buy one. My buddy has the Yamaha 2 but he won't let go of it.

I burned up a brand new Yamaha 2.5 getting the G-32 home from Alaska. It was spectacular with plastic parts dripping off the motor and a toxic cloud pouring into the cockpit. Yamaha gave me a new one as they couldn't blame it on me. I was taking very good care of it and was getting close to 50 mpg with it. one fifth of a gallon per hour at 5 knots. Had fun getting the boat the rest of the way home.

That's closer to 28mpg but still fantastic. How did the Yammer die?

FWIW, I owned that Suzuki 2.5 and loved it. I'd still have it if I hadn't sold the Walker Bay in favor of a Craigslist Avon RIB with Merc 15hp 2 stroke. 

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My math skills aren't the most reliable. My quick figuring did seem a bit too good to be true.

They never would tell me what failed on the outboard, but it wasn't the cooling system. Had it been cooling, the warranty wouldn't have covered it. Glad you liked the Suzuki. I need to find something that fits through a hatch that's less than 11" wide. Hard to find those kind of spec's.

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If I still had that Suzuki, I'd measure it up for you but if it doesn't, I think the Honda has a good shot at it. The air cooling makes it a bit more compact but, of course, you need to make some provision for it to breathe.

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On 5/9/2021 at 5:51 AM, Max Rockatansky said:

 

9/15 tends to be the same engine with different tuning, btw

I looked into that when I got my Johnson/Suzuki - big difference is the throttle body. Much larger orifice on the 15. And some other tricky little throttle-related gadget that I don’t recall exactly ATM.  Adjusts something at higher RPM.  Anyhow, didn’t have much luck finding the parts on line.     I prolly don’t need the extra 5hp, but somehow feel deprived without it. :unsure: 

Oh wait, did I have something on-topic to contribute?  Ah, that was it: weight.  Stuff left on the deflateable dinghy floor (e.g. the fuel tank) when it’s hanging works with gravity and bumps and hot sun to peel away at the glue seam holding the floor in.  When it’s floating, on the other hand, water holds the stuff up. After the second time I glued that thing back in, I stopped leaving anything in the dinghy (when it’s on a trailer - no davits, but the principle is the same.) At least that’s my current interpretation of what’s going on. 

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On 5/9/2021 at 7:28 PM, Russell Brown said:

Glad you liked the Suzuki. I need to find something that fits through a hatch that's less than 11" wide. Hard to find those kind of spec's.

I just checked mine (2020 Suzuki 2.5), and it's too wide. Main power head itself is just under 10" wide, but the tiller sticks out enough that it will need a 12"+ opening.

Honda's official spec for the 2.5 is 11.2" wide, so that might work.


Since it won't get much use I'd keep an eye on Craigslist for a nice 2hp 2-stroke. They're significantly narrower, and probably happier sitting at a weird angle in a locker.

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Thanks for that. I have been looking for a 2 stroke for a while. The Yamaha 2 hp is just tiny and would be perfect for the purpose. 

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  • 4 weeks later...

Thank you all.  I’ve learned a lot.  
I can upgrade my bent davits and score a 3-5 hp used two stroke for around 1000-1500usd.  The little motor will go on the rail.   The big motor will stay at home.  
Cheers to Garhauer for great support.   Don’t underestimate shock load    

 

 

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  • 3 weeks later...

I bought a 2.3 hp Honda.  It actually fits in the lazerette.  Also ratchet straps.  I’ll replace that one davit eventually but managed to get it sorted enough for my summer trip.  
The Tohatsu 9.8 is great, idles super quite and with patience gets two people on a plane and will maintain it at 3/4 throttle.  The 2.3 Honda is super light, simple, compact and louder, like a small modern motorcycle.  The Honda is easier to start and perkier than expected.  

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