# 25 HP Yamaha on 1645 Xtreme



## mattmass (May 15, 2020)

Need some help. I have a 25 HP Yamaha fourstroke on a 1645 Micro XL Xtreme. This is a non tunnel boat. I have added a 4 blade powertech 10 p with a permatrim. I still cannot raise my hydraulic jackplate more than an inch maybe 1 1/2 inches before blow out. I have tried the manual "trim" on all settings with all similar results. The top speed I am running is about 24 mph solo. I just feel like I should get a bit better top end. The hole shot is nothing to brag about either. Boat rides flat, but it doesn't jump out of the hole by any means. Just curious what prop y'all may be running on a similar set up.


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## Silent Drifter (Apr 29, 2021)

Thats a sweet tinny 👍 your running power tech? They dont have the answer your looking for ? I worked with Ken hes pretty sharp has lots of knowledge and notes im sure and yes you should be bustin 30 Plus i would think ....

On the prop 10 pitch sounds kind small but your numbers and performance show you could use more cup whats your RPMS thats what tells the real story?you can not properly prop a boat without RPM and wot numbers!

Off topic but is that transducer in water when running if not it could over heat they depend on water to stay cool under operation 🤔


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## MikeCockman (8 mo ago)

Not really answering your question, but I run a 25hp 2s on my 14’ Randall Craft (fiberglass/wood) with a 4 blade alum prop. 10x12p. Solo I’m running 29mph with a good hole shot. However I still can’t raise mine either. But ya definitely need a tach to get some numbers to better answer your question an address your needs.


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## permitchaser (Aug 26, 2013)

Nice boat. Looks like your cav plate is above transom. If I run my boat with the engine all the way up it won’t go fast and stays level


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## mattmass (May 15, 2020)

permitchaser said:


> Nice boat. Looks like your cav plate is above transom. If I run my boat with the engine all the way up it won’t go fast and stays level



Its a hydraulic plate. I just had it that high cause the ramp was pretty shallow.


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## jddonnelly264 (Feb 14, 2020)

It looks like your running a long shaft motor on a 16 “ transom. It doesn’t mater if your getting high enough to blow out. You need to get a tac even a tiny tack would help. You got to know what yor rpm’s are? You may be hitting the rev limiter. With out a tunnel a 3 blade of larger dia may perform better! 

with out a tunnel you would be hard pressed to go higher with out additional set back. Be careful and install a water pressure gage. If it’s a Al. Hull it’s easy to add a self venting tunnel with out breaking the bank. I can help with deminsons !


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## Mardar1 (Aug 7, 2019)

Question on your compression plate , what the width of your??. I made one for my 20 HP Suzuki, running jack plate on a Ankona Shadowcast 16
I made it plate width 12 '", but took it off. Now running without it ,due to the plates edge were catching and causing the boat to be unstable
I got about 2.5 in up before it blow, I didnt think the whole excise was worth it. 
I running a power Tech SS 3 blade 9.5 x 8 p 1Xcup and getting mu 6250 rpm Max 6300
one guy - 24 mph and 2 guys 20 , but that two flat guys
see pic
thanks for any info


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## MikeCockman (8 mo ago)

Mardar1 said:


> Question on your compression plate , what the width of your??. I made one for my 20 HP Suzuki, running jack plate on a Ankona Shadowcast 16
> I made it plate width 12 '", but took it off. Now running without it ,due to the plates edge were catching and causing the boat to be unstable
> I got about 2.5 in up before it blow, I didnt think the whole excise was worth it.
> I running a power Tech SS 3 blade 9.5 x 8 p 1Xcup and getting mu 6250 rpm Max 6300
> ...


I’d been considering building one myself and wondering if the effort would be justified or just open the door to another rabbit hole.


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## Mardar1 (Aug 7, 2019)

mike
- brought alum sheet off internet 1/8" 18 x 24 " cut myself 12 x 20 , but I had a buddy that had a break for edges 
it to wide , so I will cut down to 8 - 10 ", see what that guy in Miss posted says on the wide of his


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## MikeCockman (8 mo ago)

Mardar1 said:


> mike
> - brought alum sheet off internet 1/8" 18 x 24 " cut myself 12 x 20 , but I had a buddy that had a break for edges
> it to wide , so I will cut down to 8 - 10 ", see what that guy in Miss posted says on the wide of his


Keep me posted if you don’t mind. I’ve been kicking around the idea of building one myself, either out of aluminum of glass. I like the Tran shape and look.


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## Mardar1 (Aug 7, 2019)

trans shape looks right but I didnt want send 300 on a guess


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## MikeCockman (8 mo ago)

Mardar1 said:


> trans shape looks right but I didnt want send 300 on a guess


Same. Hence the desire to build one..lol..


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## mattmass (May 15, 2020)

Perma trim was right at $100 and I think that was worth it just from the performance differences I have seen. I did buy a Powertech SRA 3 10 Pitch and gonna see how it performs. The width of the permatrim is 10".


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## Snakesurf (Jun 18, 2019)

Not sure if this was addressed but propper cupping should help it hold water. I am on the 3 blade side without a tunnel. Trim tabs may also help it channel water to the center. I would also mount the transducer just to the starboard side of the jack plate and have it flush with the bottom of the boat. I have mine mounted that way and it works good underway.


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## TxSalt (11 mo ago)

Out of curiosity, have you ever run it without the cavitation plate? With the jack plate and no tunnel, I’m wondering if the cavitation plate is necessary?


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## mattmass (May 15, 2020)

I did run it without. I couldnt raise the plate hardly at all before blowout. Now can get it higher once cavitation plate was added. Going to run it today with new prop and see how it handles.


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## mattmass (May 15, 2020)

Just got back from running it. Top end 25.6 mph. Hole shot was better, still cant raise jackplate more than about 1-2" while under power before blowout. It honestly runs better with the stock aluminum prop instead of anything else I have tried.


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## mattmass (May 15, 2020)

After playing with the manual trim settings, I was able to get a little more top end out of this prop. It topped out about 27.5 MPH which I am happy with. I also installed a tiny tach on it and at that speed am bumping 6200 RPMS SOLO. Have not had a chance to really play with it with someone else in the boat. I am thinking about adding more cup to prop to bring RPMS down just a bit @ WOT and add some more bite in turns and possibly get the opportunity to run the Jack Plate a little higher when needed. Does anyone know of a good contact to Cup and Tune props??


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## jddonnelly264 (Feb 14, 2020)

Matt a jack plate will never provide top performance with out a tunnel to bring up the water column to allow you to run clean with less foot in the water to cause drag. You are over rpm range for that motor should be 6000 top end for a light load. More cup will help with blow out and jumping up , add a little speed.

Trying to run higher with out a tunnel or sufficient set back to allow the water column to rise can cause a problem with cooling issue. You need to install a water pressure gage to insure you are keeping a stead stream of water to the pump and not sucking air. When it starts Fluctuating in pressure your running lean on water uptake and could do damage!


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## jddonnelly264 (Feb 14, 2020)

Matt if your going to run with out a tunnel look into Smakdaddy’s low water pick up. If you add sufficient cup you will run as high as you want. With out danger of overheating and frying the motor. Use a bullet nose cone to reduce drag and clean up the water column soy you get better flow around the prop and use more of the blade for propulsion. Do not use a low water pick up on the nose, they can cause more problems than they solve. Changing the profile is benifical , especially if converting to a tunnel or smackdaddys pick up system


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## mattmass (May 15, 2020)

I just sent the prop to Jack Foreman last week to have him work it. I have considered looking into the Low Water pick up. However, at the end of the day, I mainly fish a local lake, a few local rivers, with the occasional trip to the White for trout and about a dozen trips a year to LA Marsh. I have never had the need to run for long periods of time in shallow water, most of my shallow running is to get into ponds, etc. I understand my boat will not be as capable as a tunnel. However, I just want to set it up to perform as well as possible for what it is. Other than that, I love the boat! Runs great, poles incredibly well, and is actually a very comfortable ride.


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## jonny (May 1, 2007)

You may want to try some wedges. That transom looks pretty squared up. It basically gives you setback as you raise your motor on the jackplate. Letting you get in a little higher water. It’s definitely cheaper and easier than the other options. You will lose a bit of your motor trim.
That little extension lip at the bottom isn’t helping the water come up. It’s just keeping it down longer. May want to grind it down as well


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## jddonnelly264 (Feb 14, 2020)

Your going to burn your motor up. I hope you have installed a water pressure gauge. When pressure drops are fluctuate you are running lean on water intake and not cooling properly


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## mattmass (May 15, 2020)

Yes! Installing a water pressure gauge on it this week. Thanks for all the input, will update once I receive the prop back from Jack.


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## Cassio (Dec 12, 2021)

Did you send your own powertech prop to him?


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## mattmass (May 15, 2020)

Cassio said:


> Did you send your own powertech prop to him?



I did! I just got it back earlier this week. Got it on the boat and now just need time to go run it! It didnt sound like he was in great health at the moment, So it took a little longer then normal to get back.


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## jddonnelly264 (Feb 14, 2020)

What was the outcome of the custom prop work


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## mattmass (May 15, 2020)

I cant believe how much it changed the entire performance of the boat! I am still at the 26-27 mph top end. however, I can raise the motor all the way up and the prop still bites! Same for any kind of turns as well. I am very happy with the outcome of it.


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