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RL24, RL28, and RL34 Trailable Yachts
from Rob Legg Yachts
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RL Yacht Owner's Discussion Forum
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Return to the Forum List |  Re: fitting outboard to an RL28 | Peter.
Is the diesel motor in your boat a sail drive, or a convential installation under the floor? which ever it is, there should be no problem converting it to an outboard, and I would be happy to advise you further.
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| | Re: fitting outboard to an RL28 | I went through a similar exersise on my RL24 where I moved the outboard from a stern bracket into the well.
The significant issue was finding a modern powerhead that would fit in the opening and under the tiller. The need to tilt the outboard inside the transom was also a challenge.
Cutting the hole in the hull to allow the outboard to sit in the water was done with a holesaw making each corner then an angle grinder cutting out the remainder of the panel.
New outboards have significantly bigger power heads and covers plus a variety of control positions. Most won't suit the standard position and openings.
The fuel tanks on the RL24 are placed in shelves each side of the outboard so I can safely hold about 70 liters of fuel for the longer cruises. I ended up using a 5hp outboard with high thrust propeller for the 800kg RL24, its proved to be the correct power for the lighter yacht.
Vibration and noise from the outboard are issues. My guess is a Mercury/Mariner/Tohatsu 9.8hp four stroke short shaft outboard with high thrust propeller is a good starting point then compare all the other outboards to that one. Look carefully at the 8hp and 10hp offerings from Suzuki, Honda, and Yamaha. Ultimately buy from a local dealer who will provide good service in the future.
Measuring the outboard from its pivot point to the top of the power head and tip of the propeller then checking the radiuses under the tiller and inside the stern are critical dimensions.
I always planned to build a trap door for the opening but have not bothered because I cruise and its more to go wrong.
I am not sure whether the RL28 well was designed for a short shaft or long shaft. The RL24 well is designed for the short shaft and it works fine in all conditions. Tilting the outboard up infront of the stern is important, the reduced drag makes the world of difference to sailing comfort in heavier weather.
Don't be fooled into believing you need more power, 10hp will drive the boat at hull speed easily and into decent headwinds safely. Bigger heavier outboards are not worth the hassle.
Electric start is a good option.
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| | Re: fitting outboard to an RL28 |  Hi Peter,
I am sure Rob can give you all the information you need so best to take advantage of that offer.
I note that some advice is to put only a 8 or 10hp outboard which would make the job easier. Swan has a Honda 15HP (4 stroke) and a previous owner fabricated a good set up as the thrust plate where the outboard is bolted hinges forward. See pic. It is a tight fit but works well. 15HP? I appreciate the extra power especially in a Moreton Bay chop into a headwind but each to his own.
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| | Re: fitting outboard to an RL28 | Rob, the powerplant is a Bukh 20HP 2cyl unit with a shaft drive....weighs ummmmm.....alot!
I do have another boat so I won't be boatless while I undertake this project.
I envisage a system similar to the Kestral Aloora, where they use a short shaft motor and the mounting plate slides upwards (though I can be open to other Ideas from people who know)
I am not particular about the hole being covered while the motor is up......I'm way past racing.
Looking forward to hearing from you .....especially you Rob.
My sail number is 37 and the boat is a Mk2 with the sliding hatch
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| | Re: fitting outboard to an RL28 | Peter, I was aware that there are several RL28s with larger outboards. There is not a lot of difference between the Honda 15 and Honda 8/10 so maybe the Honda 15/20 suits some people. I like Hondas but they are big and heavy.
I had a Magnum which is a similar weight length and windage to the RL28; it had a 10hp Yamaha high thrust outboard in the well which was more than adequate. I have motored the Magnum into 40 knot winds on Lake King and found the 10hp more than enough.
There were several Magnums operating with 8hp Yamaha outboards in their wells, there was no measurable difference between the 8hp and the 10hp.
The big hassle with larger outboards is the difficulties lifting the outboards out to get them serviced and lost space in the cockpit when they are tilted. A few inches of space near the legs can make a difference to comfort for the helmsman on long trips.
Like most yachts, the RL28 is sensitive to additional weight and where that weight is placed, keep it light and the sailing performance will remain impressive. I only cruise, sailing efficiently in my RL24 still gives me a big thrill even without others racing me.
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| | Re: fitting outboard to an RL28 | Hi Peter,
We don’t race either but when we are sailing we do fit a plug into the bottom of the outboard well as this cuts down on noise and stops water splashing in. Sailing should be a quiet activity so we go all out to achieve that! The plug is a pain to put in but I have improved it to make it fairly less trouble than it was originally. It does give us about ½ a knot speed improvement I think.
As you are going to be cutting into the boat, an improvement you may like to consider to improve the fluid dynamics and negate the need for a plug is to remove about 100mm or so from the bottom of the transom over the width of the outboard well to allow free flow of water past the transom. This will also improve motoring performance, noise and back splash.
Suggest removing up to the rudder lower bracket; I do hear Rob gasp in horror! Then replace this bracket with a (much) wider stainless steel plate perhaps to the width of the boat which should negate any weakening of the structure.
WARNING. I have not attempted this as I would have to pay for the work and I am not at all qualified in this area. So, I would definitely talk with Rob or a shipwright if this idea appeals.
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| | Re: fitting outboard to an RL28 | Peter.
Ouch! Russell's idea may have merit, but his boat an ex charter boat with extra ballast will be lower in the water and more prone to wash in the well. There are many boats with the standard set up in the well and I have heard few complaints, but any input would be welcome.
There were several ways in which we finished off the unused outboard motor well when an inboard motor was fitted, so a good starting point would be to take a photograph of the interior of the well, and in particular the bulkhead at the aft end of the cockpit so we can use copies to draw the detail and dimensions required for the fitting of the outboard motor, also it would be a good idea to decide on what motor you are going to fit before you start,so that the cut outs are accurate.
Standard short shaft motors are ideal but unfortunatly over the years the cowlings of some makeshave increased in size for the same power and no longer fit comfortably in the well, and some require the tiller to be hinged to facilitate tilting, any advice from current owners would be a help, there is some handy information in Surveys---Motors fitted to RLs that would help make a selection.
Don't be in too much of a hurry toseal off the holes left in the hull when you remove the motor, they needto be cleaned up and thoughly dry, then I will tell you an easy way to seal them off so it will never be obvious that there was ever a hole there.
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