Which First Boat -For River/Canal Cruising

Alicatt

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I’m using a 13hp inboard with saildrive on my 7.5m canal/riverboat, it gets me to hull speed and lets me cruise at around 8km/h, not the fastest boat around but lets me get to the speed limit on the local canals. I know of two other boats like mine and they have 45hp and 60hp engines and I have been trying to find out what they are like, a bit more grunt to push against the flow of the rivers here would be handy, as it is I would have to plan my river trips to go with the flow or the tide on the tidal sections of the local rivers.
 

Refueler

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The problem of having a bigger engine - is not so much the size - but the prop pitch etc.

Unless propped for thrust - they are generally for speed .. so become a bad choice for chugging along on a river.

I know it was estuary / Solent .. but I remember the difference on my Snapdragon 23 when I changed from a standard Yamaha to a Mercury Saildrive. Despite them being similar HP - the Mercury SD was a complete total improvement as it was designed for the 0 - 7kts .... and to plug on into tides etc. But the Yam ... it could get my Snap up to a higher max speed in calim waters - but soon lost out in any tide etc.
 

Momac

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The flows on the river Trent can be strong and up to 3kts especially on the tidal river so being under powered is not what you want.
Okay 40hp might well in theory be overkill on a 25ft river boat if you never intend to go as far as The Humber but it should be more than capable / eg should not overheat if required against strong flows. If too little power is available this could result in difficulty in making progress.

The Fossdyke of course has no significant flow ordinarily. But where the navigation exits Brayford pool and becomes the River Witham there can be strong flows when water levels are high. On such occasions some extra horsepower may be welcome.

Trapped boat rescued from Lincoln's historic Glory Hole
Screenshot 2024-06-07 09.46.36.png
 

Refueler

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I can only agree with "Momac"

Low or adequate power can leave you rather embarrassed ... but having larger with reserve power can really save the day .. having been a Langstone Harbour boater for many years !! before moving my boat to Latvia.
 

Ferris

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Some of the comments about that Shetland being ‘overpowered’ with a 40hp are quite amusing. It’s a small Honda, not a Mercury 2.5. It will have a perfectly low minimum speed and the boat has a 3/4 length keel to help maintain direction at low speeds and when in neutral. The boat is 2009 but the engine is 2014 which means someone wanted it that size for a reason, also it’s relatively new which is a positive. Either way, there’s loads of these available so the OP can decide if thay want one and can then buy whatever one they like.
 

Dannyc

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Being a novice it is interesting reading the different view points on motor power etc. I will be wanting to spend a fair amount of time travelling on the Trent, so I’d certainly like to know I had enough to fight against the flow.
 

jandnrowe

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Hi all

Newbie here so please go easy on me.

I’m looking to purchase my first boat. I’ve found numerous similarly titled threads on here, but none seem to match my criteria.

I’m thinking something used, 20 - 24 ft, easy to helm, and suitable for a weekend to a few days away. It would need to be 4 berth and would be purely for river and canal cruising, so no coastal blasts. A shower and toilet would be a must. I live on a marina and have my own mooring, so there are no concerns about mooring or trailer weights etc. I’d be on the Fossdyke, Witham, and (once a little more experienced) the Trent. A key point is that the boat would need to fit through the glory hole at Lincoln. Price anywhere between £10-25k

I’ve been trying to swat up on what may or may not fit the bill, but I’m torn by some of the advice I’ve found. Looking to just cruise along the rivers and canals at low speeds, plus being a novice, I’ve seen advice to avoid big engined stern drives like the plague. Which is a shame because I do love the modern look and interiors of many of them (Sealine, Searay, Rinker etc). Then there’re the more traditional styled boats (Shetland, Viking etc style) which again may be just the job, but I would want a young one, or one that had already been modernised/refitted as I’m really not to keen on interiors full of lots of dark wood.

Obviously many of the traditionally styled boats have an outboard, so again further conflict as I was also advised to go for an inboard, shaft, rudder.

I know the propulsion question opens a perpetual can of worms, but I’m very interested in your thoughts specific to my requirements.

Many thanks
Hello, apologies if I'm late to the topic, but I've just resolved the same puzzle as a returning/ newbie boater. After 3/4 yrs research like you I ended up looking at boats for sale in Norfolk despite wanting a boat in Yorkshire where we live.
Stay with me...
I originally fancied a narrowboat but discounted it on ground of cost - purchase, blacking etc but still wanted: diesel power, heating, shower, wc holding tank on any cruiser. The issue with canals I found was bridge clearance and specifically the offset arch effect created by the towpath. Of course it depends what water you are running your boat, but petrol is not as popular on canals. There are plenty of grp cruisers on the Broads with all of the above with folding screens. It might be worth widening your search, take your time, there are many. Who knows, we might even pass by one another.
 

ontheplane

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The problem of having a bigger engine - is not so much the size - but the prop pitch etc.

Unless propped for thrust - they are generally for speed .. so become a bad choice for chugging along on a river.

I know it was estuary / Solent .. but I remember the difference on my Snapdragon 23 when I changed from a standard Yamaha to a Mercury Saildrive. Despite them being similar HP - the Mercury SD was a complete total improvement as it was designed for the 0 - 7kts .... and to plug on into tides etc. But the Yam ... it could get my Snap up to a higher max speed in calim waters - but soon lost out in any tide etc.
Exactly my point the prop pitch is correct for the speeds you will do. A sail drive motor (sometimes called High Thrust) have different gearboxes, different size prop with a lower pitch and so forth - far superior in a tidal run.

I had a 30 Yam as an auxiliary on a 26’ Rinker - in still water it pushed it at 4knts as the engine couldn’t Rev, it was totally bogged down as propped for doing 25mph on a light RIB.

Borrowed a mates 6hp Saildrive and it achieved 5knts!! So that shows the power isn’t the main thing it’s having the thrust that matters.

Someone else said that the 40 might get the Shetland to 16knts - what’s the point when you can only do 3 or 4?

Also achieving a higher speed in short bursts is fine - but if you have a 3 knot run and have a speed limit of 5knt then you only will make 2knt speed over ground….

And a 40 will make a Shetland 535 plane (just) but not a 25’ boat weighing nearly 1500kg +
 

Dannyc

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I’m interested in the pros and cons of motor power, but the question for me as a novice/newbie is, given where I want to use the boat, should having a 40hp motor deter me from buying it, or make me reach for the cheque book even quicker?
 

ontheplane

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Neither.

Pros - the engine will be very under-stressed and if you are using on a tidal river there may be times when that extra power will be more of a help than a hinderance

Cons - 99.9% of the time if on a speed limited river you will be at barely more than tickover - most outboards are smoothest at about 2000 ish rpm so it may mean it’s a bit rougher than it needs to be (may be balanced by the fact it’s got more cylinders than a smaller motor). Unless it was specced right at the start with a very high thrust, low pitch prop then the engine may not perform properly at all, may not be able to rev properly and that might not be good for the gearbox. You will be using twice the fuel that you need to - but it will still be almost nothing so not a biggie. If you are using on a non-tidal canal then you will struggle to keep it under the speed limit - and the engine will never get over tickover.

On that size boat a 9.9 high thrust would be fine for a canal and 15 or maybe 20 at a push (again high thrust) for a tidal river is more than enough.
 

snowbird30ds

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For the waterways you are looking at it could be pretty good choice of engine, you can hop along on the tidal trent nicely and have enough grunt for a run down to hull or up to york, lower trent/ouse/humber needs a bit of power, but not silly high hp for the fossdyke/witham.
I'd be asking for a viewing and see how it drives on the river, till you try you'll never know..
 

Refueler

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Flip side - you could try it for a season and if the engine is way too powerful you could sell the 40 and get a 9.9 / 15hp sailpower /high thrust motor and have quite a lot of change I reckon

Yes.

The value of that engine in good order is worth trying and swap out if smaller will do. Personally ? I reckon you'll try it .. like it ... and keep it !!

Don't forget also that size engine will be attractive when you sell later to anyone doing estuary trips rather than canal / river. Excellent for Solent / closed bays etc.
I would not be so quick to turn away from it.

I can talk !! I just bought a 24ft MoBo with Volvo Penta 170hp ..... river has 8kt limit ... literally as soon a gear is engaged - she's at 6 - 7kts !!

BUT ... fuel consumption (petrol) is low ... lower than I expected ... about 1 ltr per knot ... at 6 - 15kts. Open throttle and of course that climbs up to figs I don't want to think about.
 

ontheplane

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The point is there is zero point in having an engine almost 4 times the power you need. Remember the old coal barges of hundreds of tons - they were moved with one actual horse power!!

The issue is that you need to check what rpm the engine will achieve - and what effect that has on speed - I bet you at tickover (circa 750-800rpm you will be getting 3-4 knots. Increase that to 2000rpm and I doubt you will be doing more than 6 knots At 4000 rpm (assuming it is propped properly and actually makes it there) it will maybe do 6.1 or 6.2 knots but burn 4 times the fuel (anyone know the hull speed of a 25’ Shetland?). I doubt it will even achieve max rpm which is about 5500rpm.

To get beyond hull speed the boat needs to “plane” something it won’t do in a river or canal as you need to be doing 12-15 knots to achielve it, something you would need 100-150hp for.

So that engine is a nice engine and pretty valuable and has a good resale value and shouldn’t stop you buying the boat - but utterly pointless on that boat.

Something like this would suit better

Yamaha FT9.9LEPL 9.9HP High Thrust Long Shaft Outboard

They used to do a 15 and a 25 which if you could find one would be even better (the 15)

Read this

https://www.yampower.co.uk/product/yamaha-outboard-high-thrust-four-stroke-ft25-ft60/

And

T 8hp - Outboard Engines - Yamaha Motor

Basically a normal outboard is designed for speed. These are for power or thrust - not same thing at all
 
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ontheplane

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Another thing is the Honda can be had with a very fine pitch prop so if that has been done it might work ok.

Some on here more expert than me could tell you what pitch it should be - I am guessing more 10inch than 19inch would be about right with a larger blade area.
 

Alicatt

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My little 2 cylinder diesel Volvo Penta with saildrive is geared just about right, 13hp and a rev limit of 2600rpm topping out about 6knots which is about hull speed for my 7.5m boat give or take a few decimal points, a bit difficult to know the actual speed through the water as I just have a GPS for my speed over ground.
Looking at more modern diesel engines, their rev limit is a good bit higher than the 2600 of the MD7A, the saildrive has a gear ratio of 1.66:1 and she is fitted with a 14" x 9" 3 blade propellor which is correct for my boat, for instance the Beta Marine engines, they rev up to 4000rpm which for the saildrive I have would be too high geared.

Saildrive1SM.jpg
 

Ferris

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You'll be fine, motor will be fine. That boatyard has several Shetlands for sale apart from the 10's for sale in other yards - look at some of them and buy the one you like the most (I would go for the best one you can for your budget).

As a newbie it might be an idea to enquire about some formal training or instruction however, even to the point of building it into your budget.
 
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