Saturn planing success!

[Chopperbill]

Started out with motor raised 3/4 inch as I wanted to raise the a/v plate because it was considered low and Tohatsu are know to have a longer shaft. Installed a Stingray hydra foil thinking I could take it off a lot easier than I could install one at the lake. Set my trim on the second hole from the transom. By myself I took a run and had to sit forward a couple of feet to get It to plane. Is did so fairly fast but was sure squirrelly and wouldn't respond well with the rudder. I hit 16 mph! Pretty good for 5000 feet I thought. But. I was getting some over transom splash. Messed with the trim but where I started was the best. Decided to take the 3/4 inch shim out just for experiment. All that was different now was the Stingray. NO over transom splash at all and was a lot more responsive with the rudder and a hell of a lot less squirrelly. I was very surprised and very happy! Only thing I can attribute it to was the Stingray. When I looked at the GPS it showed a max of 17 mph. Can't expect more than that.

 

[brook011]

Nice work!

 

[fbpooler]

Love it when things come together.

 

[Guest]

Looks like a lot of people over think the problem when an issue arises... Hmmm where did i get that from? Anyway great job!!! Enjoy your hatsu

 

[Chopperbill]

Yeah, lots of discussion about hydra foils. Some for, some against. When you are limited in horse power/weight and transom adjustments, that the big boys have, the hydra seems to a valid option.

 

[fbpooler]

Drop in horsepower but added lift at transom sure did it for you. It would be good to hear what happens at sea level.

Once you have enough power to get a boat on plane, a small increase in power does not make the difference in top speed you might think, We have run with both 9.9 HP and 15 HP on a couple of boats and the speed change was small.

 

[mrdrh99]

I can't wait to put the 14hp on my mini cat next week! I bet it will fly!

 

[Sea Rider]

Assume you're running with removed shim from transom , right ? once on plane check where water flow is passing by at lower unit. Will it plane same with 2 up ? How about overall performnce at close turns, prop ventilates ?

Happy Boating

 

[Chopperbill]

No shim, motor sitting on standard transom. Turned great as sharp as I needed. Going two up tomarow. Did not look where water was flowing as I was just happy with performance, can look tomarow.

 

[Sea Rider]

With 2 up, sit extra boater up front or on removable front seat if sib has one. Once on plane, check water flow where exactly is passsing by. Sorry to be picky on this particular point, but the whole deal here is to find the sweet spot that has the least lower unt drag for 7.5 HP engine to deliver it's fullest HP. If it's an issue looking side of engine while sitting on tube, sit on deck.Once you know exact height you can fine tune transom/engine height accordingly to achieve top combo performance.



Happy Boating

 

[Chopperbill]

Well, 2 up the dang thing won't plane. Passenger only weighs 130#. Only do 8 mph. Water is running just below top plate with just a small amount of transom back splash. Tried all trim holes. Hard to believe only 130# will take me from planing at 16 mph to no plane and 8 mph. Just ain't got no HP at this altitude. Looks like I either get a bigger motor or leave the wife home. She wont stay home or spend any more money cause she is happy going 3-5 mph. Looks like I'm stuck. Oh well I'll give em hell at sea level in AZ.

 

[Sea Rider]

The worst mistake everyone is doing is playing with engine trim, when that setting needs to be left untouched at a hole that gives an engine sitting at 90° or perpendicular to water level once sib rests on water. Then must go for an engine/transom height optimization. Make a 1/2 wooden shim and trial sib again, check if flow passes slightly under lower deflector plate. As said before you need flow to be cut right under the sharp edge located right under deflector. Right now you're dragging the lower unit with flow hitting upper deflector plate and engine is not achieving fully its limited power.

If combo doesn't want to plane with 2 up, try same you alone and visually check water flow at plane, have you measured your transom height. Asking this because Tohatsu engines performs top with 40 cm height transoms and 45 diam tubes. Which tube diam is your 365 Saturn ?

Happy Boating

 

[fbpooler]

Looks as if new jets/prop change may get you up on plane. You are on the ragged edge with two up it seems.

 

[Chopperbill]

The worst mistake everyone is doing if playing with engine trim, when that setting needs to be left untouched at a hole that gives an engine sitting at 90° or perpendicular to water level once sib rests on water. Then must go for an engine/transom height optimization. Make a 1/2 wooden shim and trial sib again, check if flow passes slightly under lower deflector plate. As said before you need flow to be cut right under the sharp edge located right under deflector. Right now you're dragging the lower unit with flow hitting upper deflector plate and engine is not achieving fully its limited power. If combo doesn't want to plane with 2 up, try same you alone and visually check water flow at plane, have you measured your transom height. Asking this because Tohatsu engines performs top with 40 cm height transoms and 45 diam tubes. Which tube diam is your 365 Saturn ? Happy Boating

Tubes are 18" which is just under 45cm. Transom it self is 15" which with the 3/4" shim would put me right at that 40cm measurement. But with that shim I was getting transom back splash when riding solo. With that little dip in the keel where it attaches to the transom I am not sure where to measure, like I said in another post.

 

[Sea Rider]

Don't worry, was just a refference. When optimizing engine/transom heights locally, personally don't care which sib or engine brand they are, just go for a wot spin as stated, go from what was achieved to dial water flow skimming slightly under water deflector plate. Know it could take its time, but once correctly dialed will live boating happily forever.

Being way underpowered and boating at 5K elevation, what you need definitely are 3 things : Engine/transom perfect match optimization, high altitude carb re jetting, less pitch prop engine maximization. Fun starts when combo is on plane and you feel the breeze on your face...

Happy Boating

 

[Chopperbill]

Real happy with it running solo. Called a Denver dealer because they are at this altitude. Didn't think jets were my problem. Told him I was happy with it running solo but not 2aboard. He said all I would have to do is change props. But all he had was 5 pitch but did not recommend it. Mine has a 7.5 pitch and that is available smaller is a 7 pitch, 6.5 apparently were discontinued. Will just a small pitch change do much, doesn't seem so to me?