Yamaha High Thrust / Kevlacat 5.2 Repower

[fly_1]

I raised this topic a few months ago, and after lots of research etc, I decided to repower my 5.2m Kevlacat. I have just put the boat in for its first service after the repower, and thought I would fill you in on the performance/details etc. Its got 2006 model EFI High Thrust 60hp Yamahas onit, and it goes bloody well! Compared to the 2 strokes (70 hp yamahas), its performance out of the hole is almost as good, I get 30kts WOT, and cruises around the 23-25kt mark at around 4500- 4700rpm. These power settings are almost identical to the 70hp 2 strokes. WOT is reving out at 5800rpm (target from yamaha is between 5300-6000rpm).
We have changed the original dinner plate sized props with 15 inch alloys ( at the moment), although after speaking to a few guys from the fishing club, I may put a couple of solas s/steel ones onit.
The ultimate test was a few weekends ago, when we went over to Tangalooma for the day with my brother and his boat. His boat, "Tanjian", is an identical 5.2m kevlacat with 70hp 2 strokes onit. It has identical fuel tank size, and set up, so it was a perfect comparison between the two. Heath had 2 extra people #in his boat, but otherwise we were pretty much identical.
After crossing the bar at Caloundra, we headed straight out towards Moreton.We both sat on about 24kts all the way. The first big thing we all noticed was the noise!! Or lack of it with the 4 strokes!! We, ( on #Wasabi) were able to listen to the stereo all the way over, compared to the crew in Tanjian who had to yell at each other everytime they wanted to speak.
We went from Caloundra bar across to Moreton, cruised around the wrecks for a swim etc, then down to the resort for lunch and a few more drinks. Then it was back up the inside of the passage through the narrows back to the ramp at the coast guard.
We filled both boats straight away, and the results were amazing!! Heath put 120l in Tanjian, and I put the grand total of 68l in mine!!! Almost half, which surprised the bloody lot of us.
A couple of days later, we loaded the boats up and headed out to the banks for a snapper session. Same boats, same weights etc , and the same results. ( By the way, we both got a heap of snapper as well!!)
So overall, I am very happy with the boat and performance I am getting with the new donks.
I know there was a few other blokes looking at doing the repower as well, and all I can say is do it!!! You wont be dissapointed!!
I wouldnt be surprised if the brother also does it to Tanjian in the very near future.

Regards

Trent

[boatboy50]

Very good report, on a very good boat.

Well done Trent, can I ask what was the final decider for the Yams over the ETECS or Suzuki four strokes? It's a very competitive market.

Who got the sale and fit up?

Regards

Darren

[Sportfish_5]

Nice rig Trent - they are as rare as rocking horse doo doo on the used market. Have heard excellent reports on those EFI 60s (great power to weight) and your report again backs it up. I thought the "high thrust" donks were for pontoon boats - what is the difference ? just prop ratio ?

Cheers

Greg

[boatboy50]

Hey Greg,

Changed the name I see? Still boat less?

The high thrust engines actually have a bigger gearbox, off the bigger engines. It allows them to spin a physically bigger prop to allow better pushing of heavy weights with smaller motors.

Regards

Darren

[Angla]

It's good to see a great comparison on indentical boats with different power plants. The results would have to be conclusive for anyone thinking about changing.

I had a similar change when going from a 5.2 metre boat with a 115 hp Evinrude 2 stroke carby, To a 5.75 metre boat with a 135 hp Mercury Optimax. Fuel used for similar trips was down by about 1/3. Money staying in my pocket every trip was, and still is great.

Angla

[fly_1]

To answer the question on the engine choice, it was pretty simple with a bit of research. The suzukis would have been great, but on the 5.2m kevlacat you really have to watch the weight. I am lucky to have a good friend ( who happened to design the 5.2, and all the original kevlacats), so after talking to Fred it was alittle easier to make the decision. The suzukis are approx 50 or so kg heavier per engine compared to the yamahas, and the etec have had a shocking run with problems with the local pro fisherman, so it really was not hard to narrow down the field. A few of the local pros have done over 3000hrs on the yamahas ( although not the EFI models) and apart from regular services etc, they havent missed a beat.
The high thrust models are 60 hps with commercial gearboxes ( same as in the 100hp ), and are extremely torquey, robust engines. With the commercial / over gearing in the engines, and the proven reliability with the local pros, they were the logical choice.
The new kevlacats have much larger pods, which can handle the heavier engines like the suzukis, so the weight issue isnt such a drama.
Overall, I am very happy with the engines, and the way they perform on the boat, and look forward to putting another 300-400hrs on them this summer.

[Smithy]

Trent,

did you go with ultra long legs like Bruce did on Shikaree?

[Sportfish_5]

Darren

Yep still boatless but saving hard to get my "Dream" boat this time. Had to change the name as it was reminding me I sold it.

Have to do something with that avatar too but cant do it just yet :'( :'( :'(


Cheers

Greg

[reef_king]

go the four strokes :), there really is no other choice in my mind

[fly_1]

Gday Smithy,

Yes I am also running the 25inch legs. I was lucky in the fact that my old engines were also the extra long models, so I didnt have to modify ( add the extra height) to my pods. Both Tanjian and my boat already had them, so it made the change to the 4 strokes that little bit easier.


Trent

[mirage]

Bout time you got it on the water. :D
Haven't got a spare bait board have you Trent? Mine still hasn't materialized. >:(
Weather is crap down here, so you're not missing anything.
Scotty.

[finding_time]

Thanks for linking to this post Mirage as i have looked for it before;)

Trent

I brought Bruces 5.2 kevlacat Shikaree and am getting similar figures to you re. milage. I'l guess i'll catch up with you one day at a SCGFC meeting or comp

Ian

[Dean1]

VERY interesting figures indeed!!! Thats made my mind up on what boat and motors to get.. Im hunting for a 5.2 kc at the moment, thanks to everybody here for your help in this matter.. There hard boats to find but the right one will pop up eventually. Go the yami f 60"s!:D

[FNQCairns]

Sounds like the perfect setup for your rig and esp so as you went from a 3cyl in a 2 stroke to a 4cyl in a 4 stroke so it turned out very well, enjoy the economy and the quite rides.

Great write up!

Cannot get that from a magazine!!

cheers fnq

[goldcoastau]

I second you with a vote for the Yammies.Found a 92 model Markham Hookem Dominator cat 5m with 2 black anchors 60 hp(Merc,s) on the the back. Fell in love with the boat.
Repowered with 2 High Thrust 60 Hp standard leg Yamaha,s.Could not be happier.Just bloody magic. Running at 50 kilometers. Solas prps cupped 13,s and Solas Foils.We run with 5 - 6 blokes spearfishing with all our gear . This is a good set up for rough offshore conditions.Boat loves to eat rough stuff.