aux engine size for motor boat and tender ?

[worlock]

I have a 25 ft bayliner cruiser and I am looking to buy an inflatable tender with an engine to save rowing effort.
Is a 3.5 hp engine powerful enough to also use as an auxillary for my main boat ? She has an auxillary engine bracket and it is mounted down quite low so a long shaft engine is not required. I see an auxillary engine as being suitable if she has enough power to move the main boat from a sticky situation to one where i could anchor safely.
I realise that this idea would mean hauling the engine from the tender onto the auxillary bracket and this can be a pain, but i don't intend to be doing this often. The auxillary engine is more likely to remain on the auxillary boat bracket of the main boat.
I realise that i would have to try this setup out to see if a 3.5hp engine is powerful enough for my boat, but i thought some of you guys may have some experience with this ?
Thanks
Mark.

 

[peterg]

Years ago (in Kim's day) MBM did a trial of this type of thing and they found the best solution was to use the dinghy/outboard combination to push the mother vessel rather than try to use the tiny outboard on the mother vessel itself /forums/images/graemlins/wink.gif

 

[jhr]

I don't think 3.5 will be enough to move a 25 footer, particularly against wind or tide. To get any meaningful movement you're going to need more like 8 or 9 hp, imho, which (a) will be OTT for most dinghies and (b) you probably wouldn't want to be trying to mount on the transom in any kind of chop.

All imho

 

[DAVIDO]

We used an 8hp on a 26ft Bayliner and found it all but useless against the tide, also it would cavitate as the bathing platform was too close to the transom for it.
As previously stated it is also not wise to try and fit the auxillary whilst out at sea.

 

[duncan]

simple answer - no

[ QUOTE ]
I see an auxillary engine as being suitable if she has enough power to move the main boat from a sticky situation to one where i could anchor safely

[/ QUOTE ] if it's sticky you will realistically need about 8-10hp as already suggested.

Could I move it with tender and 3.5hp - answer yes. in a chop/breeze/current - nope. wind/tide - no no no

For your stated requirements I would have the tender and 3.5 with a view that I get off in the sticky situation I can't anchor in (not quite sure what this might be though..? - can't anchor and can't safely drift sounds like the sort of place that (1) you should avoid anyway (2) isn't going to give you time to lower the auxiallry, prime and get it fired up and running either.

I have a 25ft single engined boat, a 4hp OB and a good tender - riggin the latter to drive the boat wouldn't come into the equation; not least because it would run out of fuel before getting me anywhere pushing a couple of tons! Better to get in tender or drift/anchor my way in the general direction I wish to go.............

 

[ms1]

is this for tidal or non-tidal situations ?

 

[Wiggo]

I tried an alongside tow a boat identical to yours, Duncan, with our tender (25hp), and while I could move it, there was almost no way to steer it. Towing from the bow was absolutely hopeless.

 

[duncan]

I believe the trick is to ensure the driving engine is behind the stern of the boat being 'towed' but I agree it's the last thing I would be attempting if I was in any sort of sticky situation.

 

[davedpc]

I think the only way to parallel tow from a smaller boat is from right back on the rear quarter with along bow tow warp forward to the bow of the longer towed boat. The stern warp to the stern of the towed boat should be short and slack in order to change the attack angle of the tow boat. If that makes sence. Dave.

 

[Nick_H]

This question comes up regularly and unfortunately the answer seems to be that there is not a suitable compromise that is powerful enough to move a small cruiser, yet light enough to transfer onto the kind of tender you would have on a small cruiser.

The answer seems to be to keep your main engine well serviced, carry spares, and maybe join Seastart, a sort of floating RAC, but they do not cover all areas.

 

[landlockedpirate]

I had a 26ft Bayliner with a 5hp on the back. The one time I tried (just to see if it worked) it was useless. Would agree with comment above, at least 8-10hp longshaft.

I did however tow my 28ft sportscruiser with my 2.6m zodiac and a 3hp Yamaha when we had a total electrical failure about 1 mile off in Menorca. Progress was slow, no tide of course but against about 10kts wind. Would only do this again if similar situation i.e. slight sea and full day light.

 

[gimmesunshine]

I have an s28, 4.5 tonnes, and twin engines. I have used a 4hp to move it into deeper water, at 2-3 knots. So it has got me out of a situation. I did this by dropping dingy in (snap davits) and turningengine thru 90 degrees. Worked a treat. Other stuck peeps were amazed as we tootled past and found the channel. This was in poole harbour, not open water, but its useful to know.

 

[truebrit]

I have a 20' Bayliner and have used my old 5hp suzuki to get me out of trouble , but I would think that you would be looking at 8-10hp for your boat , heavy enough to require permanent mounting Im afraid .

 

[Stoaty]

I have a Duver 23, about 3 tons all up with crew and fishing gear. A 5hp aux will move me at 2 knots and at 4 knots with the <u>leg raised</u>. In reality 4 knots is not enough if you have tide and weather against you. In my opinion 8-10hp is about right

 

[ShipsWoofy]

Something that is always forgotten with these conversations is the term auxiliary.

Maybe this is something cruising sailors are more common with, for instance, if the wind blows up and getting to home port is untenable we will turn about and find a safe alternative where the wind and conditions allow.

Most weekends during the summer, cars full of other peoples crew are dotting between harbours dropping skippers off to pick up their vessels. Mobo's will most often have raced home before the weather, or just pound their way back to home port.

A small auxiliary may not get you home, but it will get you to a safe haven and open up your options for repair of the main machinery. My 2.2 mercury with the tender rafted will push my 26ft 4 tonne catamaran at around 1-2 knots. This is adequate for sailing to the closest harbour and using the tender config to get us to a mooring / pontoon etc.

Or I guess like many boats there is always the option of calling the lifeboat, personally I prefer to be as independent as possible.

By the way, there is nothing stopping you carrying a large sculling oar, I have sculled a 9 tonne trawler home, ok we all took turns as we near passed out, but we got her home.

Also nothing stopping you fitting a small emergency mast and a square sail, this if nothing else could assist the o/b or scull.