Not the usual question.

[Solent Bombard]

Right I'm guessing most posts about power and engines is how can I make my boat go faster.

Well that's certainly something I don't have a problem with as I have a 135 on a 5.8m boat and excess power is certainly something I'm not lacking.

But short of changing the engine is there anything I can do to try and tame the power delivery from the engine like maybe more blades on the prop or different pitch.

As when I'm increasing speed there is a definite light switch moment of just getting on the plane to warp speed 9.

And coming from military 5.4 seariders and inboard Atlantics its a whole different ball game.

Also experienced my first tank slapper in a boat today which was entertaining to say the least

[Bigmuz7]

Its just the weight set up you need to figure out to avoid the chine walking then, and careful use of your trim, I had exactly the same rig , and it was a bugger for doing that, especially on calm seas .. quite alarming .. I take it the engine is a Mariner ?

*Edit* which I bought in 1999 ... have you got my old boat ?

[Solent Bombard]

Yep it's your old boat

[Bigmuz7]

OMG are you sure ?

[Solent Bombard]

Yeah one of your early northcrafts from my detective work searching threads on here.

Orange northcraft with yellow and black name on rear of tubes.

Mariner 135 and roller coaster 2 trailer

[Bigmuz7]

Originally Posted by Solent Bombard

Orange northcraft with yellow and black name on rear of tubes.

Mariner 135 and roller coaster 2 trailer

Well I didnt do the nameing stuff I dont think I ever named that one, but it did get the transom built up about 1.5 inches due to it taking water in at rest in waves,because of the weight of the motor and lack of weight up front,..... with that, the engine got lifted, and that didnt help the chine walking issue at all. I didnt really appreciate the dynamics back then like I do now because it was my first real RIB .. got any pics ? I'd love to see them

[Bigmuz7]

Oh I see the Northcraft name was yellow and black just found an old pic

[Bigmuz7]

this one ?

[Solent Bombard]

Picked it up from Loch Lomond it seems it has been hanging out there for the past few years in different guises and owners.

But had it up around 40-45 knots on a glassy Loch Lomond and it chine walked badly then at WOT.

But won't even get near WOT down here in the solent I reckon too much chop.


But have been overhauling the boat the past couple of months getting the hull repaired, filling numerous screw holes in deck, ripping out and replacing all the wiring and getting the engine serviced and repaired after one of the voltage regulators caught fire while at our local engine "SPECIALIST"

[Solent Bombard]

Originally Posted by Bigmuz7

this one ?

Yep that's it some things are different now though got double outhill jockeys to go in the rear and starting to get the rollers on the trailer upgraded as the indespension ones are tonk

[Bigmuz7]

Originally Posted by Solent Bombard

Picked it up from Loch Lomond it seems it has been hanging out there for the past few years in different guises and owners.

But had it up around 40-45 knots on a glassy Loch Lomond and it chine walked badly then at WOT.

But won't even get near WOT down here in the solent I reckon too much chop.


But have been overhauling the boat the past couple of months getting the hull repaired, filling numerous screw holes in deck, ripping out and replacing all the wiring and getting the engine serviced and repaired after one of the voltage regulators caught fire while at our local engine "SPECIALIST"

Fantastic I do wonder where some of my old boats have gone

As I said , flat calm was its enemy at full bung, a chop is much better , but it slapped and slammed badly in it sometimes .. the bow is so slender and without chines that if you took the sea at an angle it made quite an uncomfortable ride . You need to experiment with some ballast in the bow It was a fine enough boat .. apart from Northcrafts tube work . How is the engine ? it used to die pulling up a skier , it had some kind of flat spot where there was no juice .. is that what you were referring to in your original post ?

[Solent Bombard]

Not experienced any flat spot but just engaged it goes along slowly and then once it pops over the plane it's off like a rocket.

The throttle is like a light switch though I'm use to heavier boats I guess where you push the throttle fully open and it slowly gets up to full speed.

This boat you move the throttle once on the plane just a centimetre or so and your hanging on for dear life.

Best way to describe it is like having a V8 in a range rover and flooring it and having a V8 in a F1 car and flooring it the power delivery are worlds apart.

But designing a bow locker for the boat at the moment and was worried about adding to much weight in the construction but I'm not too worried now.

[Bigmuz7]

Originally Posted by Solent Bombard

Not experienced any flat spot but just engaged it goes along slowly and then once it pops over the plane it's off like a rocket.

The throttle is like a light switch though I'm use to heavier boats I guess where you push the throttle fully open and it slowly gets up to full speed.

This boat you move the throttle once on the plane just a centimetre or so and your hanging on for dear life.

Best way to describe it is like having a V8 in a range rover and flooring it and having a V8 in a F1 car and flooring it the power delivery are worlds apart.

But designing a bow locker for the boat at the moment and was worried about adding to much weight in the construction but I'm not too worried now.

Well 2 boats after that one was an 8.5 with a 275 Verado .... it was like shit off a shovel compared to the 5.8 ... but no doubt the chine walking on the 5.8 seasport wasnt funny .. it is violent and not for the faint hearted .. On the original config as you can see there was only a central jockey so when I first experienced it .. my crew were equally frightened, as they were not seated internally

[Under the Thumb]

Mine's a 5.5 Northcraft with a 150 Opti. It too is a bit lively at WOT but that's jsut shy of 52Kts so i doesn't stay there for long.

We do use WOT for getting me out of the water wakeboarding and monoskiing,

I had to add a bow locker to mine too- and big anchor and lots of chain - to keep the nose down, the previous owner kept a 25l can of water in the bow.

It is now fantastic, up on the plane in what feels like a boat length, cruise at 35Kts then it'll push you back in the seat again flooring it to 50.

I've also added 2 single jockeys behind the console which are great, but at low speeds - sub planing, 6-8Kts, the extra stern weight produces a massive wake.

[Major Martin]

Good grief ! That Mariner looks a total beast on your Rib and I am smiling immensley at the co-incidence of you two owning the same beast at one time......Happy boating to you both.

[uncle al]

chine walking ? put a sack of sand in the bow to keep its bow down that will do it, before I retired a few years ago we had a boat with a 135hp on the back, and the royal marines wanted to slow it down, we spent several days doing this that and the other, we slowed it down by about two knots, in the end the R.M.s put a bag of sand in the bow.

[Bigmuz7]

Originally Posted by Major Martin

I am smiling immensley at the co-incidence of you two owning the same beast at one time......Happy boating to you both.

Cheers fella .. It was my first ever RIB so has a special memory for me Not to mention some of the ones it generated .. such as me loosing my footing and slamming the throttle forward by accident whilst coming off the top of a 40 foot swell

[Festinghouse]

on the suject of the engine, is it one of those mariners that runs on two cylinders at low speed for economy, then suddenly runs on 4 for power?

[Solent Bombard]

Originally Posted by Festinghouse

on the suject of the engine, is it one of those mariners that runs on two cylinders at low speed for economy, then suddenly runs on 4 for power?

Don't think so the engine is the old carb model and its a v6 so I reckon all cylinders are open at once as it really lumpy when at very low revs

I reckon only injection model engines do the cylinder opening and closing thing

[Bigmuz7]

Originally Posted by Solent Bombard

Don't think so the engine is the old carb model and its a v6 so I reckon all cylinders are open at once as it really lumpy when at very low revs

I reckon only injection model engines do the cylinder opening and closing thing

This 135 was the smallest of the V6 2 strokes in their range at that time and they do run on all six, it was the model below (115 cant remember if its a 4 or 3 cylinder) that shut off some cylinders and thats why I specced the 135 as the smaller motor was exceedingly lumpy, I was advised by the dealer.