Replacement Outboard for 18' Yacht

[Monzu]

Hi all,

I've got an 18' bilge-keeled yacht which I keep on a drying mooring on the River Crouch (Essex). For the last year I've been using a Seagull Silver Century Plus (nominally 5hp) which shifts the boat perfectly well, but is pretty noisy, thirsty, and can be a bit grumpy when it's most needed. I've been mulling over whether to buy a newer outboard, around 5-6hp, which may inspire a bit more confidence. My budget is limited, around £250, and I've seen a few Mercury/Yamaha/Tohatsu/Mariner longshaft outboards that look like they fit the bill. So, onto a few questions:

1. Would a standard longshaft from one of these companies fit the bill, or would I specifically require a 'saildrive' model with a shallow pitched prop? The second hand longshaft models that I've seen online seem to have quite shallow props which I presume are designed for displacement hulls.

2. Is one of these motors likely to propel my boat to hull speed? The tide is pretty ferocious where my boat is and working against it, when needed, is hard work. The present Seagull has a huge slow turning prop that's supposed to work well for a displacement hull. I'm slightly concerned I may expend money and effort and end up with a motor that's not much better than the existing one.

3. Obviously this is a pretty broad question, but is this budget likely to find me a relatively-reliable engine. Clearly I can't afford one that is particularly modern.

Thanks in advance.

 

[LONG_KEELER]

Just a little bit more info with regard to the boat.

What boat is she and will the outboard be in a well or on the transom ?

Im aware that the ebb runs hard on the Crouch.

 

[ProDave]

My 18ft boat (Frolic 18) that I sold earlier this year had a 4HP 2 stroke Mariner. That would not quite get it to hull speed (I could always sail faster than I could motor) 5HP would have been better.

I found the Mariner a good engine, but twice had to de clog the fuel tap.

One of the boats I now sail is a Sunray 21 and it's mariner 5HP pushes that along nicely. The 5HP also has the advantage of a remote fuel tank option.

At the other end of the scale I sail a Leisure 17. A new Tohatsu 3.5HP 4 stroke pushes that along nicely and with astonishing economy. We did a 10Nm trip under motor and it did that with just half a gallon of fuel.

At your budget it is going to be second hand, so personally I would opt for the light weight and simplicity of a 2 stroke.

 

[peteK]

I had a 5hp Mariner 2stroke on a 19ft Seawych which was fine so I would say a 5hp or a 4hp saildrive engine would be ok.

 

[JumbleDuck]

I used, in sequence, a Seagull 40, a Yamaha 4 and a Seagull Silver Century on my Jouster (21', 1 tonne). All did the job just fine. I currently have a 5hp Mariner four-stroke on my Drascombe Longboat (22', 1/2 tonne) and that's fine too.

 

[FulmarJeddo]

Years ago I had a Sunstar 18 bilge keel yacht (stretched Leisure 17). It had a transom hung standard prop 4hp Johnson long shaft, that pushed it along admirably until the water got rough when the prop kept coming out of the water. I later had a lift keel Jaguar 21 that originally had an old Yamaha 4hp that was ok but not great. It was about the time that 2strokes were about to be outlawed, so I bought a Mariner 4hp Saildrive while they were still available. The difference was incredible. It seemed to have far more power.
I would think in your situation a standard 4hp what be sufficient, a saildrive would be ideal.

 

[Quandary]

My experience was long ago with an Achilles 24, a small boat for its length where I found an 8hp. Yamaha worked well, but much more recently I had a single engined mobo where I wanted an easily manhandled outboard as back up. Most outboards that I could manage to deploy and stow where just not powerful enough but I found an ideal solution.
A 9hp. Tohatsu two stroke weighs less than a 6hp. four stroke and with the 4 blade sailboat propellor (which costs around £100) has bags of power for even the most adverse conditions, easy to manhandle and can be stowed any way up. Problem is they are now much sought after and therefore expensive second hand. I think you can still buy new ones from Guernsey (outside the dreaded EU) if you are prepared to be a bit economical with facts about what it is wanted for.

Edit. Stupid me, I had ignored your budget, fell free in turn to ignore my post.

 

[Monzu]

Thanks for all the replies. Really useful.

The motor is destined for a Sunstar 18, as said by FulmarJeddo a slightly stretched Leisure 17, by the same designer. The outboard sits on the transom and has a tendency to lift out of the water in a short chop.

Looks like I'll aim for a 5hp and see what I can find.

 

[FulmarJeddo]

Thanks for all the replies. Really useful.

The motor is destined for a Sunstar 18, as said by FulmarJeddo a slightly stretched Leisure 17, by the same designer. The outboard sits on the transom and has a tendency to lift out of the water in a short chop.

Looks like I'll aim for a 5hp and see what I can find.

I don't know if you still have the original outboard bracket, a wooden wedge shaped construction that slotted into metal runners on the transom. I improved the performance of the outboard slightly by rebuilding the outboard bracket so the outboard was a few inches lower. I'm tying to remember how I did it, but it was probably about 30 years ago. One modification I never got round to do, was converting the boom roller reefing to slab reefing. I have memories being out for a days sailing when the wind blew up to a F6 and the shape of the sail meant the end of the boom was virtually in the cockpit. I then had a long slog against the wind along a narrow channel where the engine wouldn't grip in the chop, so I ended up motor tacking for several miles to get to calmer conditions.

 

[Monzu]

Mine's fitted with a later outboard bracket, though annoyingly, it's a non-lifting version so that you can't quite get the outboard clear of the water when it's not in use.

I had the sails adjusted for slab reefing at the start of last season which has made a big difference to the sail shape. I still don't have much hope of going to windward in F6 against a chop though (I speak from experience )

 

[shaunksb]

so I bought a Mariner 4hp Saildrive while they were still available. The difference was incredible. It seemed to have far more power.
I would think in your situation a standard 4hp what be sufficient, a saildrive would be ideal.

I think it's only the saildrive that has the displacement prop as standard, the longshaft will have the same as the standard unless specified differently.

I use a 6 hp for my Jaguar 24 in The Crouch and that manages fine.

I have a 4hp 2 stroke Mercury saildrive I was going to sell on the forum after Christmas. I bought it for my 18' Juno but sold the boat to be used on Carsington Reservoir so they couldn't use an outboard so I was stuck with it.

I'll dig out a picture (or even a video) for the OP if he's interested but I won't be going to the Crouch until after Christmas now if he want's it dropping off.

_____________________________________

 

[Seajet]

Monzu,

in the name of all that's holy go for the relative much lighter weight 2-stroke Mariner; a 4 would be fine, a 5hp better. Get one with a remote fuel tank, and if poss a charging coil; the latter used to be available as kits to retrofit from Ron Hale Marine in Portsmouth, don't know if they still are but a flywheel puller would also be required, simple job though.

A Mariner 5hp 2 stroke pushes my 22' at 5 knots, I've motored across the Channel ( 60 + miles ) with a Yamaha 4 & the Mariner 5hp in calms, no trouble.

4 - strokes are incredibly heavy, and on a Sunstars' transom bracket exactly the wrong place - nothing like Arthur Howard designed her for.

I get 2.5 hours per gallon at near max power.

 

[LONG_KEELER]

There are prop options in the Mercury/Yamaha/Tohatsu/Mariner family that you make mention of.

Roughly, 7.9x9 for light boats, 7.8x8 about middle and 7.8x7 for heavy. These are stamped onto the boss of the prop and represent diameter/pitch.

As others have mentioned , there is also a prop deemed as sailing or non planing where the blades are much bigger and look like the "Mickey Mouse" ears. I do have one of these and they are great at the bottom grunt range ie. punching waves etc but I found the extra blade area caused a fair bit more drag when sailing. This of course only applies if you have to leave the prop in the water.

 

[Seajet]

I had to slightly trim the blades of my Mariner 5hp's standard prop' to get full revs - with the Sunstars' drag of twin keels compared to mine lifted I think a big or saildrive prop' would make the engine struggle to rev freely.