Tohatsu 6hp review

dylanwinter said:
I came across this

http://www.scottcarle.com/wordpress/?p=330

is this bloke right in what he says and what pitch prop might I need for a Minstrel

http://www.western-horizon.co.uk/archive_boat.php?boat_id=25

D
Click to expand...

Fine pitch prop for a slow moving displacement hull. Larger diameter than standard if available too. Large blade area as well if possible.
It will mean the engine revs higher for the same speed through the water but to get the full power you need to get to full revs.

Do they do a sail version of the engine? That will have the correct prop but does the boat need a long or short shaft? Sail versions may only be long shafts.
 
He seems to be at odds with most posters in this thread and on the subject of Tohatsu/Mariner/Mercury engines.

He doesn't say what he is trying to achieve with his boat, but seems very concerned with maximum power and WOT running.

Used in a yacht as an auxiliary that seems to be a different target.

If running the "6 pitch" prop gives more revs then it will produce more power. That may be what you need for your new boat, but it will mean slightly noisier running at slower speed.
The 4/5/6hp are all the same motor with different settings (ignition/jets?) but the extra power will undoubtedly be delivered at higher revs, so if you think you need the extra power of the 6hp then you need to fit a prop to let you achieve the higher revs.
Generally the saildrive option will achieve this.

I have found that my 5hp on a 15ft displacement boat will motor very quietly at low revs easily achieving 4 knots, slightly higher revs give 5 knots and then opening the throttle further merely increases the noise and vibration but won't get the hull past 6 knots, which is more than it's hull speed.
I don't think I need to change my prop as extra revs or power won't improve my performance. Your boat is 2.5 times heavier than mine and you may find the saildrive option a better bet. (you'll get the charging circuit as well)
You can really only find out by trying both props.

I don't recognise my motor from his "review"
 
If you get the 6hp Sail Pro one it will have the right pitch/gear ratio for your boat, be extra long leg to keep the prop in the water and have regulated rectified charging output to keep your battery happy and your cameras going. It's the dog's doodas for the application you have. Just get it and get moving again!

Edbeynon has got one for his Hurley and I've got a Yamahaha 9.9 equivalent for my boat.
 
you boys

AngusMcDoon said:
If you get the 6hp Sail Pro one it will have the right pitch/gear ratio for your boat, be extra long leg to keep the prop in the water and have regulated rectified charging output to keep your battery happy and your cameras going. It's the dog's doodas for the application you have. Just get it and get moving again!

Edbeynon has got one for his Hurley and I've got a Yamahaha 9.9 equivalent for my boat.
Click to expand...

excellent

as for getting moving......

hardly skimmed the surface of north norfolk and the wash yet

lots to see and do

http://www.youtube.com/watch?v=q5tQFzje8lk

that is the trouble with sailors today - always in a terrible rush to get somewhere

if you want to follow a quicker trip around the UK

http://www.youtube.com/user/Peter8200N?feature=watch

Dylan
 
I would be worried that a static bollard pull test will be restricted by the diameter and pitch of the prop. Once the maximum power for the diameter and pitch of the prop has been reached, the prop will be unable to transmit any more power, it will either cavitate or load the engine so you can't achieve maximum revs as seems to be the case in this test. Once you introduce the dynamics of the boat moving, you should get the extra revs and power again. I think of it as rather similar to the way a car needs more power to get it moving than to keep it rolling.

By the way, I love the idea of the see-through hull!

Rob.
 
I agree on both counts

rob2 said:
I would be worried that a static bollard pull test will be restricted by the diameter and pitch of the prop. Once the maximum power for the diameter and pitch of the prop has been reached, the prop will be unable to transmit any more power, it will either cavitate or load the engine so you can't achieve maximum revs as seems to be the case in this test. Once you introduce the dynamics of the boat moving, you should get the extra revs and power again. I think of it as rather similar to the way a car needs more power to get it moving than to keep it rolling.

By the way, I love the idea of the see-through hull!

Rob.
Click to expand...

I cannot see how a strain guage test could make any sense at all

it has to be dynamic while the boat is moving

see through hull would be great

it would make finding stuff so much easier

one day, one day

D
 
Last edited:
I have no fancy figures to back this up, but experience with a variety of kids/engines/inflatables all used round the marina on Windermere.

Because of the lake rules, kids can only have 4hp engines (Of course if you buy the right one, it can be 'tweeked' ;) ) and being kids they race each other every where.

From memory I have seen no speed difference between the engines, with 1 up they all do about 12kts. Engines that my sons friends have include 2 stroke Yamaha, Mercury and Tohatsu and 4 stroke Suzuki (Most popular), Tohatsu and Mariner. The 2 strokes do seem to have better acceleration on the lightweight inflatables.

I dont know whats caused the problems with the reviewers engine, but I dont think theres any signifiicant performance difference between the engines.

The prop however will make a huge difference to performance. For instance my 8hp Yamaha comes with a 8 1/2 x 8 1/2 prop as standard (Its the highest pitch they do for that engine) but for heavy/displacement craft Yamaha recommend a 8 1/2 x 6 prop.

I would suggest you get the corrct prop built in with the purchase deal, cos even small props like this can be nearly £100 ! :eek:
 
Ironically- and don't take any serious notice cos your mind is probably set and researched all ready but- if it were I, an 8hp Yamaha/Japanese twin with the leg and electric start n all would be what I would want for messing around inshore through dodgy overfalls and inlets and wind over tide.
Ironic because fair weather sailing a 5 or 6 would be fine, going cross an ocean a 5 would be fine and easier to lift and store.
More conflicting 'advice' eh?:)

On a Corribee 4 was too little IME but 5 with sail prop was perfect( v skinny hull though). On 28ft fin and skeg, 10hp twin was enough to run inlets in wind over tide, Suzuki being notably better than evinrude for quality IME .
 
We had the standard prop on our tohatsu 6 on our hunter delta it was absolutely fine don't bother with a sail drive prop IMHO. You can always add it at a later date if your concerned.
PS blatant plug I have got a similar mariner 5 for sale in the for sale section.
 
Dylan

I used to run a 6hp longshaft tohatsu 2 stroke with a 3 bladed sail drive prop supplied as standard.

This was good but the control at lower boat speeds was really enhanced by converting to a four bladed Solas high thrust prop.

This engine on a 1.75 tonne TS was just about adequate but not man enough into a force 4-5 headwind and a lumpy sea.

Our recent move to the Menai strait with 5 knot tides prompted me to source a 9.8Hp engine. I initially tried without the high thrust prop. It was the best magimixer ever all froth and no go!

Fitted with the high thrust prop it is a dream. Loads of power and grip on the water.

The high thrust four bladed prop also works better in reverse than the standard prop.

I know your concerns regarding the environment but the 2 stroke 2 cylinder tohatsu is hard to beat in terms of power/ weight and LACK OF VIBRATION.(you can actually run them on 100 to 1 mix)

The single cylinder 4 strokes are horrible for the booming and induced resonance that the single unbalanced cylinder gives.

Whichever way you go definitely go for the Solas 4 blade high thrust prop. the only problem is it may not be compatible with the 6hp single 4 stroker.:mad:

If you can go twin 4 stroke I think there used to be a downrated Honda 9Hp sold as an 8HP. This has been recommended to me but is an older model and does not feature in their new range.(probably because of the ease of uprating)

One observation

The new 9.8 is a standard shaft in a well and works as well as the longshaft with the exception that we seem to pick up much more seaweed on the prop than before.
 
weight

TSB240 said:
Dylan

I used to run a 6hp longshaft tohatsu 2 stroke with a 3 bladed sail drive prop supplied as standard.

This was good but the control at lower boat speeds was really enhanced by converting to a four bladed Solas high thrust prop.

This engine on a 1.75 tonne TS was just about adequate but not man enough into a force 4-5 headwind and a lumpy sea.

Our recent move to the Menai strait with 5 knot tides prompted me to source a 9.8Hp engine. I initially tried without the high thrust prop. It was the best magimixer ever all froth and no go!

Fitted with the high thrust prop it is a dream. Loads of power and grip on the water.

The high thrust four bladed prop also works better in reverse than the standard prop.

I know your concerns regarding the environment but the 2 stroke 2 cylinder tohatsu is hard to beat in terms of power/ weight and LACK OF VIBRATION.(you can actually run them on 100 to 1 mix)

The single cylinder 4 strokes are horrible for the booming and induced resonance that the single unbalanced cylinder gives.

Whichever way you go definitely go for the Solas 4 blade high thrust prop. the only problem is it may not be compatible with the 6hp single 4 stroker.:mad:

If you can go twin 4 stroke I think there used to be a downrated Honda 9Hp sold as an 8HP. This has been recommended to me but is an older model and does not feature in their new range.(probably because of the ease of uprating)

One observation

The new 9.8 is a standard shaft in a well and works as well as the longshaft with the exception that we seem to pick up much more seaweed on the prop than before.
Click to expand...

Great stuff here

I am frightened of going up in size because of the weight

am I wrong?
 
dylanwinter said:
the anser is yes

I wil need to be able to get it on and off the boat

and put it away in the cabin for security, longevity of the engine, and to allow me to use the little honda

Dylan
Click to expand...

Then everyone is correct, the 8hp is just too heavy, lifting it cleanly out of the well or cabin without damaging bits of boat would be virtually impossible. Of course if its really heavy no one would be able to nick it anyway :rolleyes:

6hp Single cylinder 4 stroke is your only option (Tohatsu do a nice Saildrive version). Unless you want to go old school and buy a well looked after Yamaha 8hp 2 stroke twin at the same weight as the 6hp 4 stroke ?
 
You must log in or register to reply here.

Share this page

Top