Finally Powered to my liking!

[Tomfoolery]

How's about some pics of the new engine, mounted on the boat? Especially from the back and from inside the cockpit (good for scale, as I'm used to looking at the BF50 from the ground, and from the helm ).

[SENCMac26x]

I took my new 2014 Yamaha 70 out Sunday with a 14x11 Alum prop and hit WOT @6200 doing nearly 24~25mph (with the current and wind, so that could be inflated a bit).

2002 26x, empty ballast fairly light load and 3 kids and 2 adults...mostly in the cabin and no boom, just bare wires and mast.

[vkmaynard]

How fun is that!

Victor

[fouz]

Sounds like a good match. Congrats.

[mastreb]

You must have the perfect prop--that's the absolute max I'd expect to see from 70hp. Congrats!

[mallardjusted]

I was finally able to get out and give the new prop a try on the Yam 70. The last prop was a little flat pitched, although close to good.

The new prop is a 13 5/8 x 13. I made several runs after launching in Everett. Into the moderate wind AND current, 22 mph at 5700 rpm. With the wind and current, 27 mph and 5800-5900 rpm. So for an overall average of 24.5, I am very happy. This is somewhat lightly loaded, with ballast empty.

The "get-up-and-go" is great, and as I mentioned earlier, swinging the larger prop gives me much more control at lower speeds (docking, etc). Seems to me the Yamaha 70 and the X are made for each other!!!

[SENCMac26x]

I'm glad to see your numbers with the 13" pitch, I'm considered going to that to see what the performance is with the ballast fully loaded.

The best I was able to get is ~19mph @6100, and last time with a strong headwind it was @17.5 @6k

I'm hoping the more aggressive pitch can help me get those speeds at a lower RPM

[Terry]

Wow!, glad I found this thread!
I was recently eyeballing this (70 Yamaha) engine at the 2015 Vancouver Boat Show and it piqued my interest.
It has lost 4lbs now at 253lbs, it is 996cc 4 stroke 4 cyl with 2.33:1 gear ratio, best power/weight ratio I have seen so far. I hope to see more data on it here as folks test it out.How new is it and what prop works best?
I am still struggling with my old 2003 carbureted Honda BF50, trying to wear it out so that I can justify a new engine but it just seems to keep going and going like the energizer bunny battery commercial. I do plan on a new engine though, probably in the next year or two so I will watch for results on this motor.
There are a lot of opinions about bigger is better on this board but in the end it is how one uses their boat and like others I tend to putt along at 6-7 knots 90% of the time so I think this light weight Yammy is the way to go.
I have also found that over the years my boat keeps getting heavier with all the stuff we carry around and I don't see that ever changing, we just keep adding and never subtracting so I need more power just to get back to the original speed my honda used to get. I would also like a it more HP for all the tide gates we have here in the PNW, strong tide currents in the passes can be intimidating, even at slack. I think if I could cruise 8-10 kts at 4000rpm that would be nice.

[Starscream]

I think if I could cruise 8-10 kts at 4000rpm that would be nice.

No matter what motor you put on you won't want to cruise at 8-10 knots! Gotta pick either 8 knots and less or 13 knots and higher.

I remember trying to do just that with the new Etec and just hating how it handled. Couldn't hold a heading and was wandering all over the place. On that cruise I tried to back off on the power to get some better mileage, and ended up at something like 10 knots. It was horrible and I complained about it somewhere on this forum. The cause was well explained by Mastreb and it had to do with semi-displacement movement where the boat can't decide whether to roll into the turn like a motorboat or roll away from the turn like a sailboat, so it kinda does a combination of both and is impossible to steer. You're climbing the bow wave at this speed and that doesn't help stability at all.

I once left the keel down by accident and powered up the 90, but the boat immediately told me I was being stupid by not rolling into a turn like I was expecting. It immediately didn't feel right and I had a flashback to this forum and understood what was happening right away.

[Herschel]

No matter what motor you put on you won't want to cruise at 8-10 knots! Gotta pick either 8 knots and less or 13 knots and higher.

I have seen some of the posts around this topic and have been confused. I have a 2011 50 HP Yamaha on a 26X with medium load. I typically motor with all sails furled and main covered and both dodger and bimini up. All boards up, of course. Usually no ballast water and one or two crew. I find that 8-10 knots is a very comfortable and natural cruising speed for me. The boat is clearly on a plane at the 9-10 knot level. I just set the speed that fits the conditions and my mood and go. I have never found a difficult speed for maneuvering. I am wondering if the size/HP of engine is a variable here.

[dlandersson]

There are lots of variables. I too find my on plane at 10 knots. I prefer 6 knots, but plan B is 10 knots if I'm in more of a hurry - or just wanna have some fun/show off.

An has a better planing hull than a . It also has to do with prop, outboard, hull debris, load, load distribution, etc.

No matter what motor you put on you won't want to cruise at 8-10 knots! Gotta pick either 8 knots and less or 13 knots and higher.

I have seen some of the posts around this topic and have been confused. I have a 2011 50 HP Yamaha on a 26X with medium load. I typically motor with all sails furled and main covered and both dodger and bimini up. All boards up, of course. Usually no ballast water and one or two crew. I find that 8-10 knots is a very comfortable and natural cruising speed for me. The boat is clearly on a plane at the 9-10 knot level. I just set the speed that fits the conditions and my mood and go. I have never found a difficult speed for maneuvering. I am wondering if the size/HP of engine is a variable here.

[yukonbob]

Same here. Our cruising speed is usually 7-8 knts ballast in at 3000-3500. Drop the ballast and speed increases to 10 knts no steering issues. Only time I fight the wheel is when the waves pick up.

[Starscream]

Interesting to see the different experiences. My X is a total handful at around that speed...just a nightmare to keep on course. Everything is fine when faster or slower.

I haven't done any real studying of what the exact speeds are when the problem begins or going away but the 8-12 knots is probably in the ballpark. Next season I'll narrow it down to what it actually is. Useful to know in any case.

I still suspect my extremely lumpy bottom paint is partly to blame, both for lack of top-end and for ease of getting on a plane. The old Honda50 couldn't get past 8 mph or so with ballast in, but would shoot straight to 16 or 17 mph with ballast out. Maybe the problematic speed is more like 8-10 knots. Don't know. Will find out.

[dlandersson]

Isn't everything in Canada measured in Imperial whatevers?

Interesting to see the different experiences. My X is a total handful at around that speed...just a nightmare to keep on course. Everything is fine when faster or slower.

I haven't done any real studying of what the exact speeds are when the problem begins or going away but the 8-12 knots is probably in the ballpark. Next season I'll narrow it down to what it actually is. Useful to know in any case.

I still suspect my extremely lumpy bottom paint is partly to blame, both for lack of top-end and for ease of getting on a plane. The old Honda50 couldn't get past 8 mph or so with ballast in, but would shoot straight to 16 or 17 mph with ballast out. Maybe the problematic speed is more like 8-10 knots. Don't know. Will find out.

[Herschel]

I haven't done any real studying of what the exact speeds are when the problem begins or going away

i will watch my transition speeds more closely, too, and see what I notice. I, too, have bottom paint a few years old that needs attention. Interesting topic. I don't do water sports that require a lot of maneuvering at higher speeds, at least haven't so far. I mostly just cruise from point A to point B.