Yam F115 underpowered - Page 2

Searider · 17 September 2018, 09:37

A 115hp is perfectly "adequate" for a 655. It won't set the world on fire but should give you 3 knots or so.
My neighbour has a 655 with a 115hp Yamaha and is very happy with it.
Camel Trophy 655s came with a 130hp Honda (Thought to be a "Small" 130hp)

So, something is wrong:
1. Get the boat out of the water and open the bung - is there any water in the void. If so, drain it and investigate the source of the leak.
2. With the boat out of the water pressure wash the bottom. Weed and barnacles etc can make a massive difference.
3. Prop slip is a possibility. Mark both the propeller and the nut with some white paint. Trial the boat and see if the prop moves in relation to the nut. If it does than the prop needs re-bushing.
4. If the above don't sort the issue then I'd be surprised.
5. 150hp on the boat would be "Better" but until the problem with your 115hp is solved it may be difficult to sell.

Check the cheap and easy stuff before buying a new motor!

Searider · 17 September 2018, 14:18

I think i meant "30 knots or so" - not 3!

kalokeri · 17 September 2018, 15:23

Quote:

Originally Posted by Searider

A 115hp is perfectly "adequate" for a 655. It won't set the world on fire but should give you 3 knots or so.
My neighbour has a 655 with a 115hp Yamaha and is very happy with it.
Camel Trophy 655s came with a 130hp Honda (Thought to be a "Small" 130hp)

So, something is wrong:
1. Get the boat out of the water and open the bung - is there any water in the void. If so, drain it and investigate the source of the leak.
2. With the boat out of the water pressure wash the bottom. Weed and barnacles etc can make a massive difference.
3. Prop slip is a possibility. Mark both the propeller and the nut with some white paint. Trial the boat and see if the prop moves in relation to the nut. If it does than the prop needs re-bushing.
4. If the above don't sort the issue then I'd be surprised.
5. 150hp on the boat would be "Better" but until the problem with your 115hp is solved it may be difficult to sell.

Check the cheap and easy stuff before buying a new motor!

OK, i'm going down to the boat now and will mark the prop and nut and take her out for a spin. I won't be able to get the trailer down there for a few days but it will be a chance to check on the prop. Thanks and i'll report back.

matata · 17 September 2018, 16:14

Ill put my money on weed/fouling from three months the water and possibly water in the hull.......Nik

Capt _A · 17 September 2018, 16:37

What’s the cylinder compression?
Go to a smaller prop
Drop it by 2 pitch sizes

kalokeri · 17 September 2018, 17:22

I’ve just been in the water and gave the hull a quick scrape underneath and it’s wasnt that bad but certainly better than it was. I also marked the prop and nut and then took it out for a quick blast. Speed was no different and once back on the dock I checked the prop markings and it hasn’t moved.
There does seem to be some water in the hull but I can’t see anywhere to drain it from, I’m going to try and make up a pump with a long hose and feed it through to the bottom of the center hull.

Pikey Dave · 17 September 2018, 18:11

Quote:

Originally Posted by Searider

I think i meant "30 knots or so" - not 3!

I’d be impressed if a 115 would get 30kn out of a 6.5m, especially with a “normal” load.

Lee argyle · 17 September 2018, 18:34

Quote:

Originally Posted by kalokeri

I’ve just been in the water and gave the hull a quick scrape underneath and it’s wasnt that bad but certainly better than it was. I also marked the prop and nut and then took it out for a quick blast. Speed was no different and once back on the dock I checked the prop markings and it hasn’t moved.
There does seem to be some water in the hull but I can’t see anywhere to drain it from, I’m going to try and make up a pump with a long hose and feed it through to the bottom of the center hull.

The anchors not deployed is it ?

33JS · 17 September 2018, 18:45

https://r.tapatalk.com/shareLink?url...0&share_type=t

Same problem on a Merc 115 Opti on a 655 Ribtec. I haven't updated thread, and will, but its down to slight over-propping and marine growth!
I changed coil packs, leads, checked the sparks but it's none of those...

HUMBER P4VWL · 17 September 2018, 18:57

A 6.5 with weed on it and a load of water in the hull won’t do more than 15knots with a 115hp on. My money is on water in the hull.

Is there not a plug in the well at the back of the boat to drain the inner hull in to it?

kalokeri · 17 September 2018, 18:59

Quote:

Originally Posted by 33JS

https://r.tapatalk.com/shareLink?url...0&share_type=t

Same problem on a Merc 115 Opti on a 655 Ribtec. I haven't updated thread, and will, but its down to slight over-propping and marine growth!
I changed coil packs, leads, checked the sparks but it's none of those...

Cheers, I'm getting it towed out tomorrow on the trailer so will give it a proper clean then and hopefully any water that's inside will drain out too.
What sort of speed were you getting before you had issues?

33JS · 17 September 2018, 18:59

Quote:

Originally Posted by HUMBER P4VWL

A 6.5 with weed on it and a load of water in the hull won’t do more than 15knots with a 115hp on. My money is on water in the hull.

Is there not a plug in the well at the back of the boat to drain the inner hull in to it?

I emptied mine first, secured plug and couldn't break 22kts.

33JS · 17 September 2018, 19:00

Quote:

Originally Posted by kalokeri

Cheers, I'm getting it towed out tomorrow on the trailer so will give it a proper clean then and hopefully any water that's inside will drain out too.
What sort of speed were you getting before you had issues?

I was getting an easy 32kts! Isn't the Camel Trophy a heavier hull build with bigger tanks? Do you have the scaffold assembly on it?

kalokeri · 17 September 2018, 19:01

Quote:

Originally Posted by Iron Dials

How is the engine rigged? Is it the appropriate shaft length?
You mention you’ve put boat and engine together.

At 5000 rpm it’s not meeting much resistance from the hull (clean or dirty) so I would wonder if the prop is slipping by virtue of how is sits in the water flow.

I jumped in the water and the cavitation plate is level with the bottom of the hull.

kalokeri · 17 September 2018, 19:07

Quote:

Originally Posted by 33JS

I was getting an easy 32kts! Isn't the Camel Trophy a heavier hull build with bigger tanks? Do you have the scaffold assembly on it?

The scaffold is all gone but yeah it has the 2 tanks under the flooring.

kalokeri · 17 September 2018, 19:09

Quote:

Originally Posted by HUMBER P4VWL

A 6.5 with weed on it and a load of water in the hull won’t do more than 15knots with a 115hp on. My money is on water in the hull.

Is there not a plug in the well at the back of the boat to drain the inner hull in to it?

No I couldn't find a plug to drain it in the rear well, i'm going to try and get a pump with a long hose to feed it through so i can get access to any water.

Searider · 18 September 2018, 09:15

Quote:

Originally Posted by kalokeri

No I couldn't find a plug to drain it in the rear well, i'm going to try and get a pump with a long hose to feed it through so i can get access to any water.

On my Ribtec there's no access to the void below the sole from inside the boat. It will need to come ashore to drain the water out.

33JS · 18 September 2018, 09:48

Quote:

Originally Posted by Searider

On my Ribtec there's no access to the void below the sole from inside the boat. It will need to come ashore to drain the water out.

Interesting. I've got plugs either side at the bottom of the rear well where the bilge pump sits. The other is at the bottom of the transom on the outside to drain the hull.

kalokeri · 21 September 2018, 16:34

Ok, an update.

I managed to trailer the boat out of the water and yes it did have quite a bit of water trapped in the hull. I also gave it a good clean underneath as there we a few barnicles growing too.
Anyway, launched again and it now zips along pulling 27Kts @ 5000 rpm which is a bit more like it.

Thanks for your help guys!

HUMBER P4VWL · 25 September 2018, 10:39

Excellent news. Water weighs a lot!!!

If you want to upgrade your 115hp to a 175hp Optimax, we’ve just taken ours off as upgrading to a 200hp new Merc 4S.

Open to any reasonable offer... owned since new and no expense spared. Full documented dealer service history, low private hours and comes with all ancillaries, runs sweet as a nut, starts first time. You’d get quite a few more knots! Ticks our 6.3m along at 53mph[emoji6] PM if interested. http://www.rib.net/forum/f36/175hp-o...ale-79801.html