New Achilles LSI-365 and 25 HP Yamaha

[jimandsue60]

Hi All, I have been lurking for a while and enjoying all the info in this forum.

We have recently upgraded from a 2004 10' 4 " high pressure floor Achilles to a 2008 12' 2" LSI-365 (both hypalon). We started off with a 15 hp 2 stroke Yamaha and wanted to haul 4 adults and gear on plane with a little bit of speed, so we traded in the 15 for a 25 hp 2 stroke short shaft.

I am impressed with the performance of the Yamaha 25. We traveled 45 miles miles with 4 people and gear and used a tad shy of 6 gallons at about 22 mph, the water was pretty choppy. With 2 people and gear I am guessing a speed of 33 mph. I will be getting a gps soon for more accurate #'s.

We wanted the high pressure floor for ease of storage and less weight as we travel with this boat and motor in our motor home year round. I installed a dolfin type anti cavitation device which eliminated some cavitation issue I was having. I also installed Wheel-A-Weigh launching wheels.

Here is a picture of the boat off of Cayo Costa Island in Florida. More photos of this boat and our pervious boat can be seen here http://www.flickr.com/photos/jimandsue/

Thanks for the info.

Jim

 

[Drowned Rat]

Re: New Achilles LSI-365 and 25 HP Yamaha

VERY sweet ride! Enjoy.

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

Thanks, we have been having fun.

The waters of South West Florida have been fun, now we move up towards the Great Lakes (Lake Huron and Superior). I will keep you posted.

Jim

 

[Drowned Rat]

Re: New Achilles LSI-365 and 25 HP Yamaha

Yep, love the pics. That's what I want to do with my inflatable next. An ocean trip somewhere. We like to go to Sanibel every so often. I would love to take it there! I could explore those mangroves forever.

 

[John the Barber]

Re: New Achilles LSI-365 and 25 HP Yamaha

Really nice. I love the west coast. Much more laid back over there.

 

[John the Barber]

Re: New Achilles LSI-365 and 25 HP Yamaha

BTW. Without your permission I now use your Flickr picture of the water and clouds as my desktop background. Thanks in advance.

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

BTW. Without your permission I now use your Flickr picture of the water and clouds as my desktop background. Thanks in advance.

No problem, Enjoy!

Jim

 

[Dmitry]

Re: New Achilles LSI-365 and 25 HP Yamaha

Jim, I've got the same boat and same engine. Do you have a link for that anticavitation device? Where did you get it from?

Also, what is your experience with the floor? Mine is flexing when accelerating over waves even after I pump it as much as I can.

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

Here is a link for the anti cavitation device. I got it at West Marine http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/111619/377%20710/0/cavitation/Secondary%20Search/mode%20matchallpartial/0/0?N=377%20710&Ne=0&Ntt=cavitation&Ntk=Secondary%20Search&Ntx=mode%20matchallpartial&Nao=0&Ns=0&keyword=cavitation&isLTokenURL=true&storeNum=6&subdeptNum=240&classNum=384

According the the manual the floor needs to be at just shy of 9 PSI. If you do not have a pressure gauge you NEED to get one. My boat came with a pressure gauge, even my 2004 came with a pressure gauge.

The high pressure floors need to be at the proper PSI for best performance, other wise they will do what yours is doing. I have the foot pump but also have a 12 volt high pressure pump from Bravo http://www.waterstrider.com/raft-air-pumps.htm

Jim

 

[Dmitry]

Re: New Achilles LSI-365 and 25 HP Yamaha

Thanks for sharing the links!

Are you talking about the pressure gauge at the end of the pump that came with the boat? If so, mine has one. It keeps jumping up and down as I pump- should I look at the "up" or "down" positions to determine pressure in the tubes or the floor?

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

Yes that gauge, it only reads accurate when you step down (pressure cycle) on the pump. I put little marks on the gauge (with a magic marker) at the 3 and 9 psi marks. It makes it easier to see when you get the pressure proper.

Jim

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

I finally ran the boat with 2 people and gear using a gps. I was a bit high on my original guess of 33 mph as I only got to 28 mph.

I do seem to have a cavitation issue at times, typically with 2 or more people in the boat. The boat will be running fine and once in a while over a sharp wave or just after it gets on plane it will cavitate briefly. I did install dolfin type anti cav plate.

My anti cavitation plate is @ 2 inched below the lowest point of the transom but the v bottom of the inflatable keel is way lower than the cav plate on the motor. I am running on the lowest trim hole on the engine. I have tried the other higher positions and it only makes it worse. Being on the lowest trim setting has less cavitation issues but is harder to steer and more splash back happens

I am going to try a 1 and 2 inch spacer to raise the engine in the next few days. Any thoughts or suggestions are welcome.

We left Florida a week or so ago and spent the holiday weekend on a lake in Northern Central Michigan.

Jim

 

[Dmitry]

Re: New Achilles LSI-365 and 25 HP Yamaha

How did you paint your registration number- did you use paint or did you glue the letters on?

I do get massive splash back when at WOT with two people. How do you know when cavitation happens?

 

[Dmitry]

Re: New Achilles LSI-365 and 25 HP Yamaha

By the way, are you using the standard prop that came with the engine? Have you tried different props yet?

I've ordered the wheels to make it easier to launch the boat, should have them soon...

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

Dmitry, I used the standard stencils and a wide permanent magic marker.

When I get cavitation it sounds like the prop is out of the water and rpms go up. Maybe I am confusing this with ventilation which I know nothing about.

I am using the prop that came with the engine which has 9 7/8 X 11 1/4-F stamped on the prop hub. Maybe that can be an issue.

Jim

 

[Dmitry]

Re: New Achilles LSI-365 and 25 HP Yamaha

Yes, I have the same prop. Thinking of trying other props later this year.

What you are describing does indeed sound like ventilation. If I understand correctly the only way you can observe actual cavitation on the prop is after the fact by detecting the burn marks.

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

We took the boat out on the St. Clair river in Michigan yesterday. This is some cold water I put a 1 1/4 inch spacer under the engine and it made the Ventilation worse. The cavitation plate is level with the bottom of the transom (within Achilles specs for this boat). The trim is set at the lowest setting. Most times at higher power settings when I went over larger roller waves the engine seemed to lift out of the water and gain rpms with the flex of the boat. If I raised the trim one notch it magnified the problem.

I am now assuming that my boat needs something between a long shaft and a short shaft, which makes me think I need to trim a small section out of the transom to get the engine deeper in the water and the perfect ride I am looking for. I am open for thoughts or comments before I do this.

It is pretty neat to be this close to the 600 foot + freighters coming in and out of Lake Huron.

Jim

 

[Chris in Indiana]

Re: New Achilles LSI-365 and 25 HP Yamaha

Thanks for positng the pics, I always like to see what other inflatable owners are up to.
I was wondering what your opinion was of the Wheel-A-Weigh launching wheels. I have been looking into something like that for quite a while but mechanically speaking it seems that they would easily splay out and work against each other. It also seems that they would get in the way of the motor in the up (stored) position. I notice that they are not on the boat in your pics so do you typically take them off after launching?

 

[jimandsue60]

Re: New Achilles LSI-365 and 25 HP Yamaha

Chris, the brackets that the wheels mount into are fairly stout and hold up well. They can not splay out because of how the brackets hold them in. I have towed my boat for 8 miles (slow speed 10 mph) with no problems. I usually do take them off after launching but will leave then on if we are going to a place where there is a ramp and need to beach it. When the wheels are up they do not interfere with the engine or steering. I have found that if I tow the boat to fast the wheels can start to melt (the wheels are plastic). They were not designed for towing far or fast. I do put marine wheel bearing grease on the axle once in a while. After using them in salt water for 5 months they have no issues.

Jim

 

[becxlt]

Re: New Achilles LSI-365 and 25 HP Yamaha

Curious ..how do you attach the front of your boat to your tow vehicle . When you are using the launching wheels ?