Engine Weights

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    Posted: 10 Oct 2021 at 4:17pm
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Looking at repowering, currently have 150 Optimax, my boat is rated to 225hp and 240kgs engine weight, is there a risk if I installed an engine 263kgs?? Limited stock of all engines at the moment and I have an option in a month or so on a 2020 Yamaha 800-850 hrs.
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Post Options Post Options   Likes (0) Likes(0)   Quote MATTOO Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 5:30pm
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Some info on hull type and length, brand of boat. Type of use boat has.
How many people you carry , how much gear.
All relevant info to provide better replies.
Just cruising in my now sweetas pimped out Southern 755 HT0!
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Post Options Post Options   Likes (0) Likes(0)   Quote Fish Addict Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 5:42pm
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Potential insurance risk I would imagine.
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Post Options Post Options   Likes (0) Likes(0)   Quote Muzza-Jay Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 5:51pm
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Mclay 650 cruiser, generally 2-4 people for day fishing, Once or twice a year will take 5-6, Overnighters and longer trips 2 people but a bit more gear, food ice etc. I had been carrying 30 liters of extra fuel but with 4 stroke economy I can ditch that. Cheers
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Post Options Post Options   Likes (0) Likes(0)   Quote Muzza-Jay Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 5:53pm
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Yeh I wondered if that could be the case, I’m a bit stuck as there are next to no 200-225’s in the country at the mo unfortunately.
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In my opinion a 250 Yamaha would be a big motor on a 6.5. Perhaps you should wait.
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Post Options Post Options   Likes (0) Likes(0)   Quote Muzza-Jay Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 7:11pm
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Yeh the 250 is 255kgs still over the max weight, insurance is my concern too, I’m not sure how the insurance works with this type of thing? I’d prefer not to go with merc or 200 inline four cylinder Yamaha, those seem to be the only ones I’ve seen below 240kgs. Cheers
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Post Options Post Options   Likes (0) Likes(0)   Quote terrafish Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 7:20pm
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Contact Mclay and ask them maybe? Margins are often built in so ,may still be in spec. Worth a shot mate

Part time Devils Advocate, Fulltime procrastinator
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Post Options Post Options   Likes (0) Likes(0)   Quote Muzza-Jay Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 7:35pm
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I emailed Steve Mclay and he told me max weight 240kgs and max power 225. He suggested 200 or 225 merc.
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Post Options Post Options   Likes (0) Likes(0)   Quote Big -Dave Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 8:28pm
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The problem is not always the hp, it's the deadweight on the stern, and if the boat is a bit light up front, the bum sinks and the boat gets all tippy and unstable. Gets worse when most of the people on board rush down the back to fish or look at something. The problem is even worse on a pod, as there is a lack of buoyancy right under the motor.

Dealers have stashed motors for their own builds..
you can't fix an idiot with duct tape, but it does muffle them for a while...
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Post Options Post Options   Likes (1) Likes(1)   Quote Muzza-Jay Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2021 at 8:44pm
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Thanks for the feedback, i thought my trim tabs could help with the buoyancy or potential porpoising, I think I’m best to wait and go for the correct weighted engine. Cheers
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Originally posted by Muzza-Jay Muzza-Jay wrote:

... I’m not sure how the insurance works with this type of thing? ... 

I do.  The insurance company will be happy to take your money but in the event of a claim expect it to be rejected.

Firstly you would need to disclose it to the insurance company.  That gives them the opportunity to either provide insurance to you or not.  If they were to provide insurance you need to ensure your disclosure is incorporated within the insurance documents.       
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2021 at 7:58am
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I'm building a boat. I would be astonished if the transom could take 225kg and then break at 20kg more than that. 

People ask on the bateau forums all the time whether they can put say 100hp on a boat designed for 60. The standard answer is that although the transom could take it easily, the bottom panel and stringer layout is designed for a certain weight and speed. Increase that too much and you run the risk of a failure slamming at high speeds. Fortunately most boats are tougher than those that crew them. Almost all the time the crew gives in and slows the boat long before the structure is at risk. They just can't take the pounding that the hull can. 

 There's also trim changes to take into account. 

I'd pull the trigger on that outboard to be honest if your current one is genuinely not up to the job, and just be aware of the possible effects of heavy weather. But run it by the insurance company first. 




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Post Options Post Options   Likes (0) Likes(0)   Quote Big -Dave Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2021 at 1:56pm
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Originally posted by Muzza-Jay Muzza-Jay wrote:

Thanks for the feedback, i thought my trim tabs could help with the buoyancy or potential porpoising, I think I’m best to wait and go for the correct weighted engine. Cheers


Trim tabs only help once you are under way..
Really though, another 20 kg?, it's not a lot percentage wise, but I am aware of the negative effects of an overweight motor can cause.
you can't fix an idiot with duct tape, but it does muffle them for a while...
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Post Options Post Options   Likes (1) Likes(1)   Quote MATTOO Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2021 at 4:36pm
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You answered your own question.

Contacting Mc Clay boats was the right call.
Heed there advice.

Don't rush and make a bad call.
Adjust to conditions and keep looking for another motor..
Just cruising in my now sweetas pimped out Southern 755 HT0!
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Post Options Post Options   Likes (0) Likes(0)   Quote Muzza-Jay Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2021 at 8:27pm
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Thanks for all the advice, going to wait and see how things pan out later this year with engine imports, hopefully this bloody COVID thing settles and allows us the freedom we all need to get out on the water. Cheers
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Post Options Post Options   Likes (0) Likes(0)   Quote Joker Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2021 at 8:39pm
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Originally posted by Muzza-Jay Muzza-Jay wrote:

I emailed Steve Mclay and he told me max weight 240kgs and max power 225. He suggested 200 or 225 merc.


Those 200, 225 V6 mercs are supposed to be amazing engines and so fuel efficient. I would seriously have a closer look at them.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2021 at 9:58am
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Comments on the extra 15/ 20 kg above being ok
Totally agree.
 As to a bit over powered, only if you use it it.
 May sit at anchor 1/2" lower if anything in the water at anchor.. doesnt matter.
Will cruise more economically (10%+) at the old engine cruise speed due to less throttle , ans less load on engine meaning far leaner mixtures.
Will cruise more comfortable than before, faster and use maybe little less to same fuel as before.
 Hit chop, can set throttle and cruise thru more comfortable, slightly faster, and on an oily rag, as dont need to work the throttle.
Crossing a bar, wave stand up , have the power to get to it and thru the next wave before it fully stands up.

Down side.. must look around, ask and check everyone is holding on even on a normal hole shot.

As to trim tabs etc, will not need them because of the weight (only 15/20kg) .. you have all that extra reserve power, very little leverage required to drop the bow... And the choice of prop rake will sort that out...

Get it..

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Post Options Post Options   Likes (1) Likes(1)   Quote MATTOO Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2021 at 5:32pm
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Steps and others.
One of the reasons there are weight limits on motors is the buoyancy of the stern.
The chances of being immobilised and stern on to a sea state is the risk of swamping. It is that simple.

The power relationship is a misdirected piece of advice.
Heed the manufacturers recommendations.
Just cruising in my now sweetas pimped out Southern 755 HT0!
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Post Options Post Options   Likes (0) Likes(0)   Quote OneWayTraffic Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2021 at 11:07pm
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I'd agree if it was a 300hp he was looking to put on, but an extra 23kg? Move a battery forward if you must, or don't use the livewell. I'm not advocating that he do it, I'd be happy with the existing motor if reliable, but I really don't see this making the boat unsafe. It's the same as a child on a stern seat. 

Manufacturers don't like to exceed their margin of safety willy nilly. I understand that, but if it was my boat and that was the best choice of motor I'd hang it and not worry about a thing. 
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