Guidance on O/Board size for a 12'6" Foreland Dingy

P

PIPSQUEAK

New Member
Joined
14 Nov 2006
Messages
3
Visit site
Guidance on O/Board size for a 12\'6\" Foreland Dingy

Have been trying to locate guidance on how to choose the most appropriate sized outboard for a 12'6" GRP hulled Foreland Dingy and would appreciate advice on where to look or where to access the "rules" for calculating such things? Also could someone explain the difference (physical and peformance) between long, standard and short shafted engines?
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

outboard size will depend on application - to give you enough to stem a tide 2-3hp should be enough. 4hp should give you full hull speed on a displacement dinghy in calm water. 5-6hp will be enough in just about all situations unless you're going to load it to the gunwhales. shaft length depends on transom height. cavitation plate on the outboard should be just about on or just under the load water line.
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

I have a Foreland - gunter rigged. An ordinary 2 hp outboard is plenty. it's not really intended as a planing hull and a bigger engine is likely to case vibration.
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

Quite. I have a 4hp on an 18ft Foxhound and I rarely need even half throttle. too much throttle won't get you past hull speed. It just makes a lot of noise and cavitates. The concept that you need more power to stem the tide is irrelevant. You won't push your boat through the water much faster than it's hull speed. which for a 12 foot dinghy is about 4.5 knots.
The cavitation plate should be level with the bottom of the transom, however deep it is below the water. It can be deeper, but shouldn't be higher.
My Seagull 40Plus (about 2hp) is plenty for my 10 foot tender.
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

My tender motor, 4hp Johnson will push my Etap22i which has a 1.4m deep keel and weighs over a ton. I can't see you would need that much for a 12ft 6in dingy.
Allan
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

You have had the scientific answers about engines that are too large but there is also the comfort factor.

I used to have a 7.5hp Honda o/b on a 14ft open angling boat that I moved up from running 4hp o/b's on 12ft boats such as mirrors.

the 7.5 was smooth and would cruise at half throttle nicely. It was very much quieter than the 4hp engines, and from what I hear going up and down my harbour, still would be quieter alongside modern honda 4hp air-cooled types.

As this is a motor boat, you really don't want to spend the day shouting at each other over a crude putt putt, so my recommendation is to go for around 6hp but check for quietness also, make sure it has fwd-ntr-rev gears and a 12v output can be handy to charge a small battery if you are planning to do any night or evening fishing.

Yes, 6hp is overkill, but there is a big difference between what is usually sold as a tender engine and what would be bought as an auxiliary or main dinghy engine, I know what I am trying to say anyhow!
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

For 10 years I used a 5hp on a heavy 17' dinghy which was fine. 3.5hp on yours is more than adequate.

Consider also the weight and the fuel consumption.

Look to the experts at the Dinghy Cruising Assn www.dca.uk.com
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

I agree,have a look at the Tohatsu 3.5 as featured in PBO August '06 issue
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

Tohatsu 3.5............Mariner 3.3............Mercury3.3...........

All same engine! some with different dangly bits, but same engine. /forums/images/graemlins/smile.gif
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

[ QUOTE ]
As its a motor boat you need a back up engine as well - which can be anything small that starts and fits beside the main 3-4 hp engine.

[/ QUOTE ]

On the other hand, you could just get a pair of oars? /forums/images/graemlins/grin.gif
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

[ QUOTE ]
Oars?

[/ QUOTE ]

Yaboooo! beat ya! /forums/images/graemlins/grin.gif
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

[ QUOTE ]
Get a Seagull!

[/ QUOTE ] But which model do you suggest, a Forty Plus?
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

Vitalman wants to put two engines on what is fast becoming a gin palace - a 3 or 4 HP to get about and a smaller one just in case. Look chaps we are talking about a 12 and a bit foot dinghy which is presumably primarily a sailing dinghy. That much ironmongery on the back is just not feasible. I have exactly the same dingy and a 2 or 2.5 hp is plenty. Some cautious posters have also said take the oars which is of course essential so the only additional get you home device I can suggest is a very long warp tied to one end of the boat and paid aout from the jetty so that the back up Health and Safety team can haul the dinghy back if things get really tough.

Enjoy the Foreland!
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

Bungee elastic???? /forums/images/graemlins/grin.gif To be a little serious, a Seagull Forty Featherweight, would be ideal in my opinion, and can be had for very reasonable money, also, spares are plentiful again.

Application of the KISS principal seems the way to go on this one.
 
Re: Guidance on O/Board size for a 12\'6\" Foreland Dingy

Pretty much any Seagull will do. Second-hand and very cheap.

Look out for forum members throwing them out, under the mistaken impression something new/japanese will be better! (see recent threads)
 
You must log in or register to reply here.

Share this page

Top