Thread: Honda 100 Outboard Prop - Surtees 5.5 Hardtop

Happy new year to everyone on here. First post for 2024 as i’ve been too busy doing summer holiday things with the family. Hopefully everyone else has hooked into their own form of the same.

Alright, just before Christmas we upgraded our boat and managed to land a Surtees 5.5 hardtop with a 2019 Honda 100 outboard on the back. Bloody loving the boat, it’s been great so far and the kids are loving it too.

My question is with the prop. It’s a stainless 4 blade prop with the following numbers on it: S4X 13 1/4X15R

It seems to provide very good holeshot / get up and go but once it’s on the plane it seems to rev a lot for not much gain on top. It can also rev into redline on a nice day which I don’t think it should be able to do if propped right?

Any boat setup gurus on here have any idea what my options are? I don’t want to loose too much of the get up torque but a bit more on the top end would be nice.

Nice Boat mate

Sent from my SM-S916B using Tapatalk

Have you trimmed it right.should be at least trimmed half way and then adjust up till cavitation I find then down to where it's nice ride.obviously sea or lake conditions vary the trimming effect . I was trimming my boat only couple bars up until I was advised how to trim it properly. Obviously with prop etc some are made for more low end holeshot and slightly less topend as a offset..Maybe talk woth Honda or surtees on what is ideal prop for what your after.i know my stabi has a recommended motor mount position amd prop setting for the combo.

What sort of speed is it doing top end for the revs?

Originally Posted by Quackers

Have you trimmed it right.should be at least trimmed half way and then adjust up till cavitation I find then down to where it's nice ride.obviously sea or lake conditions vary the trimming effect . I was trimming my boat only couple bars up until I was advised how to trim it properly. Obviously with prop etc some are made for more low end holeshot and slightly less topend as a offset..Maybe talk woth Honda or surtees on what is ideal prop for what your after.i know my stabi has a recommended motor mount position amd prop setting for the combo.

This was my first thought, sounds like cavitation issue, or at least the symptoms read that way...
adjust trim as nessecary according to speed and weight on board, you get the feel for it with experience.

My mate has a very similar set up.
5.7 Surtees and 100 Yamaha 4.
It doesn’t really sit on top of the water unlike my Stabi but it does sit in the water better than my Stabi.
I’ve questioned his amount of trim but he’s adamant it’s correct.
I’ll look at his prop and be in touch mate.
His top end is fine although I reckon it could sit higher still.
Good boat and efficiency is great.
HNY chief.

Is it cavitating at all, ie getting air into the prop and reducing the friction on the water which allows the revs to rise? Cavitation is often thought of as a big lung full of air into the prop, revs scream and the forward speed dies and the boat needs to restart off from in the hole but it can be a lot more subtle than that.

The other options are trim and motor height, but if it's been set up from the dealer it should be right for height. Now prop pitching is a very user-dependent thing, if the guy who had the boat before you ran it a lot heavier than you are the prop might have been perfect for him but for your purposes there isn't the same load on the motor i.e. you are running ever so slightly 'underpropped' so the power isn't getting transferred to the water efficiently (the boat is moving forwards easier than the motor is set up for in other words).

You are correct though, it doesn't seem right that you are hitting the red line in normal operation - but it should be a relatively easy fix with a prop swap. The local dealer should have the next size up water wheel in stock and it's a quick job to bolt them off and on.

Next question is what do you want to do with the boat, as there's a conversion to be worked out if you want to go to a 3-bladed prop which might be an option for you - 3 bladed props are generally considered to be better at the top end once sized right and the 4-bladed options are supposed to have better hold at the bottom end due to slightly higher blade area for a better 'bite' at low speeds. I think for your application for the little info you have given either option will work provided it's correctly sized. A likely possibility is the previous owner did a little kid dragging on skis or toys, which would explain the expensive 4-blade wheel (better bite out of the hole). It may be that there isn't a convenient step up in pitch in the stainless 4-blade line (likely you'll be looking in the same line for a 13-1/2 or 13-3/4 pitch) which might mean you have to try a 3 blade option.

Get in touch with Surtees mate. They’ve been doing this a long time now. Prop selection is a bloody rabbit hole by the sounds of it.

You would be surprised that shops actually just put outboards on set up to Their discretion..I've seen ny same boat set with same motor with different motor mount position. When inasked the dealer I bought mine off he sent me the suggested hole mount and prop from yamaha for my particular boat.he said the other dealer had set up wrong with it being too low..if it get up to a good speed then hitting the recline isn't crucial..whondriber there car on redline the whole time .yet we own a boat and expect to drive it to its limits.

Should have provided a bit more info in the first post sorry. The guy I bought it off was doing a lot of bar crossings at port waikato to head out chasing big fish etc and he told me when we picked it up that it had good get up and go for the bar but was a bit slow on top when cruising on a nice flat day as a result.

Pretty comfortable with trimming and managing the ride etc - it does go very well.

With regards to the red line, it was a once off when I was trimmed quite a bit on a nice day and gave it the full berries to see how she went. Cavitation or redline is not a regular issue.

Our use for it varies a lot. One day we could just be me, my wife and the kids with a light load out fishing and then the next we could be loaded with four divers on a big mission. Bar crossings are not a regular for me but I will do a few.

I suppose to clarify i’m not having any big problems as such, and it goes well the way it is. I’m more looking to querry if anyone who knows props well is able to see if I could change blade or pitch a little to maybe get a bit more top end without loosing too much on the bottom. Hopefully that makes sense haha. Cheers

5000 rpm atm gives me around about 40 - 43kph if I remember right. Sorry - my brain likes to think in kph and m/s rather then knots haha.

sounds like its good the way it is..... always a swings n roundabouts kind of deal. went through the whole swapping props deal with mate years ago..seemed to me he spent a hell of a lot of coin for bugger all gain.
unless you really want more top end speed I would say leave it alone...if you can borrow a higher geared prop to try...yeah why not?? but certainly wouldnt fork out for new one if what you have is working well. we have almost opposite issue in that we want to slow boat down a flyshit at idle for trolling.

Just been chatting to the guy we bought it off and he said a 16p 3 blade is what a few people running the same boat / outboard seemed to find best so might have to give that a go.

The prop that's on is prob set for holeshot of he was doing bar crossings.thats when you need the get up and go.the top end don't matter at that point .safety paramout .

You will likely find that with the 16p 3 blade on and four divers (bubblehead math - 4 divers = the same load as 6 people so for a 5.5m boat that's a lot of lardarse) the boat will feel sluggish and not want to run up onto the plane hard. From the sounds of it it's not far underpropped, and you can control how hard the engine is working with the funky handle thingy so if it's hitting redline just back off a touch on the loud setting.

Unless you want to be changing wheels every other trip, it pays to set up for your heaviest/worst condition so if you are set up for max load and can tolerate the odd time where you're 90 seconds slower to destination it's probably good as is. Consider that if you're out and the weather cuts up unexpectedly, you'll be slowing RIGHT down and be needing to increase/decrease speed to get in around holes and big chops so setting the boat up to play wave dodge is a good place to be. Makes a lot of sense now if the previous owner was running bars for a stainless four blade prop to be fitted - they are around double or 2-1/2 times the cost of the garden variety 3-blade ali. On the subject of that, the stainless props tend to not break if they thwing a log in the water (technical term there) but they may bend the shaft which can give the gearbox shaft seal arseholes. Be aware of that if you do strike a prop, as dropping right back to minimum possible speed and checking the prop for wobble at the first opportunity could save your lower unit.