CONTINUOUSWAVE

I’m looking for some advice for [A 19 GUARDIAN with a] 2007 Honda 135-HP engine with a [three-blade] HONDA propeller 14-3/4 x 19-pitch. Here is some present data:

• At full throttle the boat speed is 36.-r-MPH and the engine speed i s 5100 -RPM.
• There is not too much flat water in Hawaii.
• At 20-MPH the engine speed is 3,500-PRM with me, 50-gallons of fuel, and my empty cooler that weighs [70-lbs]. There is no canvas or T-Top.
• The normal is crew is four adults, combined with 80-lbs fishing gear and cooler 130-lbs of ice.
• [Boat speed at full throtte] isn’t that important. Cruising speed and [and time to accelerate to plane have] even [importance]. I do most of my traveling at an engine speed of 3,500 to 4,000-RPM.

What propeller would be ideal?

Make sure tach is accurate but you need to drop at least 2" of pitch to get closer to 6000-RPM). A 17-pitch should get you to 5,500 or so at WOT.

Are you mashed to the dash with the trim all the way up and close to blowing out when you are at 5100?

WOT with trim tucked in is like riding with the E-brake on. If you are full tilt boogie, you need to drop at least 2-inches in pitch. If you are not trimmed to the max, do so and report back please.

Cruising at low RPM does not mean it is the most efficient. I looked at a 315 Outrage online and it got the same MPG from 4500-5500 rpm. You might want to look at Honda website to find a hull similar to yours and look at the performance. This can give you a good start on prop, MPG and expected top speed. I always was taught, cruise at the lowest RPM or listen to the engine where it is in its sweet spot. Not bad advice but if you see that it gets better MPG at 4000 than at 3500--well.

Here is test results from Honda: https://marine.honda.com/outboards/performance

Go to the BF135 on the Arima 19 test. Shows hull weight of 1650lbs which is probably close to a Guardian(what year Guardian?). shows a 17" SS prop hitting 42.5mph @ 6k.

In addition to what Nick stated, we need to know at what height the engine is mounted. How many empty holes above the top bolt on the bracket.

Which Solas model prop you have? Stainless or aluminum?

I think you are within 2 to 3-MPH of WOT speed but the WOT RPM you reach now is below the desired range.

biggiefl wrote:Make sure tach is accurate but you need to drop at least 2" of pitch to get closer to 6000-RPM). A 17-pitch should get you to 5,500 or so at WOT.

Are you mashed to the dash with the trim all the way up and close to blowing out when you are at 5100?

WOT with trim tucked in is like riding with the E-brake on. If you are full tilt boogie, you need to drop at least 2-inches in pitch. If you are not trimmed to the max, do so and report back please.

Cruising at low RPM does not mean it is the most efficient. I looked at a 315 Outrage online and it got the same MPG from 4500-5500 rpm. You might want to look at Honda website to find a hull similar to yours and look at the performance. This can give you a good start on prop, MPG and expected top speed. I always was taught, cruise at the lowest RPM or listen to the engine where it is in its sweet spot. Not bad advice but if you see that it gets better MPG at 4000 than at 3500--well.

Here is test results from Honda: https://marine.honda.com/outboards/performance

Go to the BF135 on the Arima 19 test. Shows hull weight of 1650lbs which is probably close to a Guardian(what year Guardian?). shows a 17" SS prop hitting 42.5mph @ 6k.

I’m not too sure where the motor was trimmed exactly. I trimmed Till it peaked.

I did 80 miles in 2 days starting with a full tank and then topped it off at the same station after and she got 4.3mpg.

Seemed like it was happier at 4K, but sometimes it just gets too rough to maintain that pace in the open blue.

I’ll definitely check out the site.

Phil T wrote:In addition to what Nick stated, we need to know at what height the engine is mounted. How many empty holes above the top bolt on the bracket.

Which Solas model prop you have? Stainless or aluminum?

I think you are within 2 to 3-MPH of WOT speed but the WOT RPM you reach now is below the desired range.

I raised the motor so it’s 2 up. Now I can see the cav plate when she’s on plane. Definitely runs better cruising, but didn’t do too much at wot. Only about 50-100 more rpm and maybe 1 mph.

Prop is stainless. Not sure of the model. Just says Honda and has those numbers.

I’m happy with wot. Obviously, faster would be cool, but I don’t really open it up often. Just want her to cruise quickly. I do a couple runs that are 25-40 miles one way.

More worried the prop is too big and stressing the motor too much or it could be more efficient.

What does trimmed till it peaked mean? Did it start to slip and then you brought it down a bit? I would prop that to run at least 5500+ RPM