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Adding a auxiliary outboard.

5K views 25 replies 11 participants last post by  Group9 
#1 · (Edited)
Hi guys, I have a Jeanneau Fantasia 27'-6" yacht. It has a Yanmar 1 GM 10 which is working fine. We are planning a UK circumnavigation in her next year and I am minded to add an outboard to her to give a bit more security in some of the remoter bits of the journey if the prop fouls or the Yanmar conks.

I got hold of the original manual for the boat and if my French is anything to go by (and usually it is not!) the transom on the Starboard side is reinforced for an auxiliary motor bracket and it does appear to be. The problem is that this is the place that the boarding ladder is now fitted. I thought about switching the ladder to Port to create space but that looks like the devil's own job and I am sure that I would need to remove the holding tank and the fuel tank to get at the fixings. I can get at the Port side, no problem, from the back cabin. I am wondering what I need to do to reinforce the transom on the Port side to take the weight and thrust of the motor. I have a nice piece of 1" teak for the outside. I am looking at bonding a piece of marinbe ply to the inside.

The motor I have is a 5hp Honda :BF5 weight 27k. Not very big or powerful I know, but reliable as hell and utterly bulletproof.

If anyone has done anything similar I would value an opinion or suggestion.

Thanks
 
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#2 ·
I have a Yanmar 1 gm. Personally, I'd go over it well (maybe with a trusted mechanic) and have appropriate spare parts, and forego the outboard idea -- especially with all the trouble you are proposing.

These motors, when in good condition, are very reliable and easy to work on if something does go wrong.

Plus, you do always have the sails as backup power (sorry, couldn't resist).
 
#3 · (Edited)
As suggested, focus on the diesel. It is more powerful and the prop is better positioned to be effective. The boarding ladder is probably mounted where it is because of the reinforcement that's already there. Messing with that will be... a mess. If you really want to use the Honda 5hp to move the boat, get a dinghy and try using it to tow, or push while tied securely alongside. Mounting an outboard on most sailboat transoms becomes ineffective very quickly in any sort of seaway. The prop gets lifted out of the water and then overspeeds and cavitates when it's plunged back in. Even Hondas don't like that treatment. Take care of your diesel and it will take care of you. Our Yanmar is 32 this year.
 
#4 ·
Make sure you use a mount that is spring loaded to assist with the motors weight and has enough travel to get deep in the water.

How thick is your transom? I'd think a 1in backing plate would suffice. We mounted one on our boat, but the transom on ours is 1/2in thick. We used a 3/4in starboard backing plate and washers, it has held up fine.
 
#5 ·
don't forget that now you need to keep another fuel tank on board with the requisite plumbing, and you have spent a ton of time and effort to add a 5 hp gas outboard in case your 9 hp diesel conks out.
What if your O/B conks out?
Spend the money you would spend on cobbling together a bastardized O/B solution and buy a couple of spare fuel filters, a Yanmar spares kit, add a bulb to the diesel line to ease in bleeding, and have the tank cleaned.
 
#6 ·
Are you taking a tender? A hip tow arrangement with a powered tender would get you out of most trouble spots if the yanmar takes an inopportune holiday.

I've also seen workable examples of an emergency outboard mount that goes on a deployed stern ladder.
 
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#7 ·
Thanks for the replies thus far. I fully intend to look after the 1GM10 which has just been overhauled and is running well and looks to continue to do so. I have read a great deal written by UK and Ireland circumnavigators about the likelihood of running over unmarked fishing lines and fouling the prop, particularly around the Irish coasts. And loss of motor power for one reason or another is the No 1 cause of rescue according to the RNLI. I am not looking for performance. I am just looking to be able to drop the motor and to use it to get back into somewhere where I could sort the situation out. I do take the point about cavitation and the need to position the motor correctly based upon the sprung bracket I have. . The motor will have a small portable tank with pipe connections which I will keep in a locker until needed. I think I will go ahead and fit it. I am going out today to look at the job before any final decision. Thanks again. And Oh yeah. I have got the sails to fall back on. Those are the floppy white things aren't they. (Sorry, couldn't resist ;-) )
 
#16 ·
I have read a great deal written by UK and Ireland circumnavigators about the likelihood of running over unmarked fishing lines and fouling the prop, particularly around the Irish coasts. And loss of motor power for one reason or another is the No 1 cause of rescue according to the RNLI. )
Losing power may be the No 1 cause of rescue for the RNLI because they rescue a lot of powerboats. Is there a separate count of how many sailboats they rescue because they lose power? Fouling the prop on fishing lines is much less likely if you're under sail. We snagged nothing on our trip, touching at Crosshaven, Kinsale, Arklow, Wicklow, Dublin, Howth, Strangford Loch, Holy Loch, Dunoon, Man, and the Scillies. Things may be different out beyond the Irish Sea, but fishermen don't want their gear damaged any more than you want to run into it: unmarked lines may exist, but there shouldn't be many.
 
#8 ·
I have often thought about doing the same thing you are proposing.

When I was cruising, I had a 25 HP outboard for my dinghy. I thought it would provide plenty of emergency power for my 42 foot boat (not to mention it could even be a lifesaver with a broken rudder) if I could figure out a way to mount it.

I haven't done it yet, but I keep thinking about using something like this.



So that if necessary, I could merely mount the motor on it, and then lower it to where it could power the boat. I have a swim platform on my boat that would allow me to reach the handle and steer it.

Like I said, I haven't done it yet, but I often think, why waste a motor and just use it for the dinghy?
 
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#10 ·
this is what I have on my boat...it was done as the old palmer p60 engine was having trouble

Im leaving it there to use a a swim ladder platform to the davit cross beam and just in case I ever need to plop on an outboard

Im looking for a 15hp was we speak

my boat is 13k displacement but I have used an 8hp yamaha to test if it moved and it did quite decently

cheers
 
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#9 ·
Oh, the best OB bracket for the money is the Garhauer OB-125.

I think I paid $180 for it and the quality is far superior to any of the others I looked at, but at about half the price. I do not know if you will be able to get it in the UK easily, though :(

Also, be wary of keeping a gas tank in your locker. We keep ours outside to prevent fumes leaking down into the bilge or cabin.
 
#11 ·
The biggest chance of having random inboard failure is when you are sailing in rough waters and the fuel tank gets mixed up and debris or water clogs the fuel filter.

Those same conditions are the ones where an outboard is not going to work well on boats any longer than 25' (unless you have a well that moves the outboard closer to the center of the boat). This is especially true of a dinghy outboard that has a short shaft.

I'd spend the effort overhauling the inboard and cleaning the fuel tank.

Having 100lbs hanging off of the stern of an average 28' boat doesn't help it's sailing either.
 
#12 ·
The biggest chance of having random inboard failure is when you are sailing in rough waters and the fuel tank gets mixed up and debris or water clogs the fuel filter.

Those same conditions are the ones where an outboard is not going to work well on boats any longer than 25' (unless you have a well that moves the outboard closer to the center of the boat). This is especially true of a dinghy outboard that has a short shaft.

I'd spend the effort overhauling the inboard and cleaning the fuel tank.

Having 100lbs hanging off of the stern of an average 28' boat doesn't help it's sailing either.
I thinking of when I get into the harbor, not when I'm sailing in a storm.

The two times I have had engine failure in 26 years of sailing, an outboard would have cured my problem.

One time, I was anchored and had run my battery down and had no way to charge it, and couldn't get my diesel cranked, and had to sail into an unfamiliar small harbor in Pensacola Bay, with the wind blowing into the harbor, and dock under sail. Not as much fun as I like.

The second time, I was coming int the west approach of Nassau, at dark. I cranked my diesel and it ran right up until I hit the entrance and then died (later found to be a blockage in the line as you describe), forcing me to sail to, and drop anchor in, a place I really didn't want to anchor, to unblock it, which took over an hour.

In either of those two cases, an outboard would have worked, and saved me a ton of trouble, which is probably why I think it's a good idea.

It's unconventional thinking I know. But, a lot of good ideas come from that kind of thinking.
 
#13 ·
same here...whats true about alex´s statement is that many deisel inboard owners never clean or regulalrily service their tanks and when the crap hits the fan no amount of racor filters help any

that and air from sloshing fuel

Ill keep my outboard bracket for sure just in case, jajaja
 
#14 ·
Unless you leave the outboard permanently mounted, trying to mount a 60 to 100 lb motor over the transom with the boat possibly bouncing around could be a real chore, even for a big strong person.

If you go the outboard route, I suggest you get the longest shaft that will fit.

Paul T
 
#15 ·
you can rig nice pulley systems on swinging mounts...plenty of cruisers use this method to simply pull the engine up from the dfinghy in the water works great

but yes its messy...quite dangerous sometimes and definetly NOT fun

but adrenaline in emergencies does wonders, jajaja
 
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#17 ·
It's that last hundred or so feet into the harbor where an outboard would usually be handy in the event of a motor failure.

I once delivered a 32 footer with a motor that would only run five minutes before overheating, from Fairhope, AL to Biloxi, MS because I knew I would only need the motor for less than five minutes on both ends of the trip. :D
 
#19 ·
It's that last hundred or so feet into the harbor where an outboard would usually be handy in the event of a motor failure.
Sure, you can add a second auxiliary and a second fuel system to get that last 100 feet. or you can drop anchor and fix the problem. As you have discovered, the problem is usually simple, and is usually the result of deferred maintenance...and let's face it, if someone's not maintaining their primary engine, think the just-in-case outboard and it's tank of fuel is going to be neglected any less?

As others have pointed out, if you have a dinghy with an outboard you already have a justincase system- adding the complication of a motor mount to the transom of the big boat is an unnecessary complication.
 
#24 ·
I've made a good living out of being able to think asymmetrically. If it was common, I'm not sure I could have done that. :D
 
#22 ·
Three pages! I never had THREE pages of replies before.

I'm going to do it anyhow. My wife is about to renew the headlining in the rear cabin and so it is now or never. I have got a garage full of outboards and intend to experiment with the one best suited to getting me that last 200 metres bearing in mind the good stuff people have said about the size of the motor.

Here is the plan. I have made a template for the inside reinforcement and I have cut the pad out from 20mm marine ply. I have drilled a matrix of holes into it and intend to initially fix it to the inside of the transom using bonding paste such as Freefix.

Freefix 6470-W-2, GRP wood bonding paste - East Coast Fibreglass Supplies.

The pad ties in nicely with the curve of the hull as it goes up. The holes should fill with paste to key it in. That done I will glass over it. to fully bond it to the hull. I have sorted out a couple of knees and will bond those in as well to add a bit more strength. I have also designed a brace which I will attach between the pad and the rear locker which should resist the pad being pushed in if someone clonks the motor. With the 25mm teak pad on the outside, I am pretty sure that this lot will do the job. It should not take long with the right preparation and being newly retired I have plenty of time anyway. I will post photos.

Thanks for all the replies. Just for the record the inboard engine has been fully overhauled, It has all mod cons, strainer, fuel separator, new exhaust elbow, etc. The tank is new stainless steel and was so clean three weeks ago that I could have drunk Jura whiskey out of it. Noone ever accused me of "deferred maintenance"!
 
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