150 hp on 6.6 Haines - Is this OK

[whichway]

Hi all

The following link is to a review of a 150 hp 4 stroke yammy on a 6.63 Haines patriot.

http://boatpoint.ninemsn.com.au/portal/alias__boatpointau/tabID__200859/ArticleID__119089/DesktopDefault.aspx

Basically the review suggests top speed of 71 km/hr, and best economy 1.8 km/lt at 4000 rpm (44 km/hr). At 3200 rpm (a speed that I often travel at) economy dropped to 1.4 km/lt.

I have a 175 2 stroke on a 6.2 Haines and frankly I don't think I would like to go much smaller.

Questions:

Does the torque curve on a 4 stroke mean that you can get away with a less horsepower than a 2 stroke.

What about the theory that a loafing motor is more efficient than a motor working hard. This motor is more efficient at 4000 rpm - hardly loafing along I would have thought.

I've spoken to people with 225 4 strokes on 6.8 Haines - usual fuel economy 1 km/ltr, and I would have thought that a 150 would be way too small for a 6.6 Haines. Any ideas?

Any ideas how to work out how a 150 would go on my boat - its a pretty expensive mistake if the motor turns out to be too small

PS I want to cross bars, so its got to get out of the hole with no problems

Regards

Whichway

[mackmauler]

How does it go on bars at the moment? what bars do you cross whichway?

Rob

[cooky]

I've got a mate with a 6.8m Haines (older hull) - he had a 225hp 2 stroke and just upgraded months ago to a brand new 250hp Merc 2 stroke. He has a friend with a new 250hp suzuki 4 stroke on same hull and didn't think it quick enough - that's why he went 2 stroke (+ saved around 10k I believe). He was telling me last week that he wishes he'd gone 300hp (max HP rating for hull). He gets good speed, but obviously likes the HP. He cruises at higher than 4000rpm. Likes his speed. I would have thought 3200rpm was just on plane.

[cooky]

and I'd also add that I would be surprised if you'd find 150hp high enough. I've got 115hp on a 5.4m and I'd love to put a 150 on it (if I had the cash).

I guess it depends on your boating style - if you like to sort of potter along most of the time then get less HP, however you've also got to think that when comes time to sell most buyers will want more GO. Particularly when you see most 6.8m Haines in trade-a-boat, etc with 2 x 150hp motors.

[SeaSaw]

I've got a 225 4 stroke on a 6.8 Haines and it is a pretty good match. I couldn't use any more power as it gets up on the plane in a flash and has a top speed of 40knots. I have never been able to travel that fast offshore anyway so 225hp is a good match in my opinion. p.s I have been averaging about 1.2km per litre.

I havn't had a good look at the 6.6 patriot hull, but I would be surpirised if 150hp is enough as it is still a deep v hull. Do you know what it weights?

I have found the 4stroke has more torque down low than my old 200 2 stroke. This gives better holding power in a big sea and a better low speed plane. The hole shot is about identical, so I would conclude the 2 stroke is a little better on raw acelleration as I am comparing a 200 2stroke to a 225 4 stroke for the same hole shot performance.

Mark

[whichway]

How does it go on bars at the moment? what bars do you cross whichway?

Rob

I cross South Passage, and it goes OK.

Whichway.

[Kerry]

That engine is also only 4 cyl and quite frankly they are having themself on. As for the loafing motor being more efficient, NO! not necessarily so but the opposite in this case appears to be pushing a motor the opposite way and considering 4S's are apparently not designed to run over or close to 80% for any length thehn it really is a few cyl's short of a six pack.

Cheers, Kerry.

[NQCairns]

Your Qs are way too specfic for me, but consider not hp or 4st/2st concentrate on thrust at the prop and RPM. Suppose a person can get a 150 to produce enough thrust to get that hull on the plane and maintain an acceptable cruising and max rpm then it is a suitable engine. The question then is how fast does a person want to travel or accelerate because a bigger engine proped well will always use more fuel than the smaller engine propped well pushing the same boat. nq

[cooky]

NQ - that's why I mentioned the 'pottering along" comment. Some people like speed, some don't. The recommended motor for my boat (and most popular) is 90HP - I've got 115hp, but I wouldn't mind 130/140hp (getting into 6cylinder). I am prepared to pay for the fuel for the speed/grin factor - but that's just me. Saying that I am very happy with my motor and wouldn't part with much or any cash to upgrade, but if someone came along with same age/hours/condition motor and wanted to swap I would.