Tender engine size?

[Eastside3]

I’m torn between going with a 6hp with an integrated fuel tank vs stepping up a size to the 8/9.9 with an external fuel tank.
I’m curious how many out there have a 6 and wished they went larger to get on plane, and are there folks who went larger and wished they stepped down. There’s about a 28lb difference in my engine considerations and my tender will be mounted horizontally. Look forward to your experiences.

 

[bluestreak]

We purchased our R-27 late last year.
It has an 8' alum hulled inflatable tender and it has the 6 HP outboard and is mounted horizontally.
Previous owner had no complaints about the setup.
We have not had a chance to try it out yet.

 

[BradOwens]

We have a Suzuki 2.5 and think it's plenty. It's small, easy to get on and off the tender, and quiet. For tender use, it has plenty of power.

 

[BB marine]

I have used and own both 6 HP and 9.9/15 hp outboard's on my Aluminum RIB. Both of my outboards are 2 stroke so the HP to weight ratio is different to a new 4 stroke. The difference in weight % of 2 strokes 6 hp and 9.9 is very similar to the 4 strokes. I was an outboard mechanic for a number of years and I'm still hanging on to 2 stroke technology! The light weight 2 strokes will out perform the 4 strokes all day long but with that comes below average fuel economy and 2 strokes are not environmentally friendly. That's the big one!

I keep the Aluminum Rib horizontally mounted.gallery2.php?g2_itemId=48507&g2_imageViewsIndex=1. I do not keep the motor mounted on the RIB when transporting using the davit. So I have to remove the motor each time I put the boat back on the swim platform. This was doable with the 6hp ( 48lbs, about 10lbs lighter then a average 6hp 4 stroke). The 6 hp would get the RIB on plane with one person and push it 12mph but with 2 persons top speed was 6 mph. If using the Rib as a tender 6mph is acceptable. If you are using the Rib as a sport dingy, exploring, harbor site seeing, a little more speed would be nice.I thought the latter would be nice so I searched for a later model 2 stroke 9.9 mercury. I located a Mariner ( same as a Mercury) It was the 15hp model. Same weight as the 9.9, same engine just different carburetor and a restricter plate. This motors weight 75lbs. 27lbs more then my 6hp but 23lbs lighter then the 9.9 4 stroke. The difference in the weight was the difference in me not being able to SAFELY remove the motor from the RIB and store it on the motor bracket on the boat. I needed a davit.gallery2.php?g2_itemId=68944&g2_imageViewsIndex=1. I installed a davit and now mounting and removal was safely achievable. The Performance was night and day. With one person in the Rib it skipped across the water 26 mph, with 2 adult persons jumped on plane and top was 24 mph. It was a fun tender.

Weight! Extra weight, That is the dilemma for me. Added extra weight at the aft section of the boat. A semi displacement hull with a LWL under 30' with a Rib cantilevered off the end of a swim platform and then add a 100lbs motor and fuel tank, along with the addition weight of some type of davit system to lift the motor and Rib out of the water. It does add up. It does change the running attitude of the boat.

From my experience with the RIB weight, the motor weight, the additional equipment needed for bigger engine. I'm going back to simple. I want a tender that weighs under 80lbs, a motor under 60lbs, capable of getting me to and from shore, capable to do some exploring, can achieve 5 to 6 mph with max of 4 passengers, Easy to launch and retrieve, and installed so it does not obstruct my aft visibility.

My advise, the 6 hp will be more than enough.

 

[TugScout]

We use the 2.5hp Mercury for our RIB on our R-27. It works just fine for getting to shore and doing a bit of exploring. It's light weight enough that my wife could attach it to the dinghy if she needed too.

 

[Smcavana]

We have a 6hp Tohatsu on our Achilles hard bottom. Planes with one person, but not two. Still need a crane to get it from the stern rail to the dinghy and back without the danger of back injury or dropping it in the wqter. We had a 8hp four stroke on our sailboat for a couple of years. Too heavy and awkward, so we went back to the 6hp. Personally, I wouldn't want to deal with an 8hp or 9.9 without one of those systems that leaves the OB attached to the dinghy but rotates the OB to vertical when the dinghy is horizontal on the stern.

 

[FlagShip]

We went with the 6 hp Yamaha for our Ranger RIB tender. Originally was going the direction of the 2.5 HP motor, but switched to the 6HP at the last minute. Glad we did.

It does weigh substantially more than the 2.5, but is doable. I'm not a big, burly guy - 145 lbs. I pull the engine off the rail mount, rest it on the swim platform while i get in the tender, then pull the motor into the tender and set it on the transom.

The 6HP gets the tender on a plane easily with just me. With me and the missus, we can get it to plane at full throttle with her on the mid mounted bench and me leaning forward almost to the bench.

 

[Eastside3]

I’m taking delivery of my new tender in the next couple of weeks (once it gets through customs). It’s an 80lb tender and I’m keeping it mounted horizontally. I’m working with a Davit manufacture to tweak one of their designs so it can meet my desired attributes. Since I’m keeping it in a horizontal position I “in theory” won’t have to remove the engine as often. The Davit will carry a 500lb load. If I find the extra aft weight between a 6hp and an 8hp ends up being negligible on how the boat performs AND If I can manage to keep the engine on the tender full time, I’m inclined to go with the 8hp..... but if I’m going to be removing the engine, even if just a fraction of the time that others do (speaking of those who use weaver davits and don’t have the option to keep it vertical), then you make a great point about the overall heft of the larger engine and being able to “safely” deploy/remove without killing my back. I’m a big guy (250) and lifting the engine on a stable surface is fine, but I’ve yet to wrestle one on a swim platform with movement.
I greatly appreciate the insight and sharing your experiences. This is most helpful.

 

[rackline]

Eastside2, please keep us posted on which Davit you decide to install. I want to install a horizontal solution for visibility and to keep the outboard installed but haven't really dug into this yet. Trick, Wise and a few others look like they would work. Some stow the dingy higher than others. Since the platform is awash at some speeds I would think higher would be better.