Saturn first outing

[Chopperbill]

Finally got in the water. Learned a lot. Takes lots of power to drag launching wheels that I forgot to put up. LOL. Run out of room in a hurry. Went back to shore and unloaded a box of gear, took out the clamp on seats and other just in case stuff we took along. Found out the best seat in the house is sitting on the floor leaning against the tubes. Found out when it it hits the water you loose a lot of air pressure, pumped it back up while in shore and put the pump in the truck. Wont plane, a disappointing 9 mph with wife, dog and cooler. Need to raise motor but am afraid I can't raise it enough so a stingray is standing by. If that won't do it that's ok cause we had a blast just cruising around the reservoir at 2-3 mph.

 

[Guest]

That 9.8 should plane the three of you no problem. Your doing something wrong. I tend to inflate my boat about 4.5 psi. So does sinister he has the same 365. Did you inflate the keel properly? Did you inflate the air floor to About 12 psi?

 

[Chopperbill]

No Title

Used these pressures. Tubes seem firm as did floor. Keel seems kinda soft at those settings. Had a new air gauge but nothing to compared it with. Afraid to over fill it. 12 lbs in floor is way over recommendations.

 

[Guest]

Used these pressures. Tubes seem firm as did floor. Keel seems kinda soft at those settings. Had a new air gauge but nothing to compared it with. Afraid to over fill it. 12 lbs in floor is way over recommendations.

You will not over fill it. I believe the tubes were pressure tested at 15psi. Your keel should be so hard that if you press it, it does not push in. Same with tubes. One quick good test i found works is. sit on the tube if you feel a small bounce then you need more air. If you sit and feels like you sat on a wooden stool then your good. That info it shows is wrong for some reason. Sinister and my self fill up the tubes and keel to 45kpa. Damn i just did the math it comes out to 6.52 psi. I do not recommend you fill up that much but make sure you don't bounce when you sit on the tube. Even at 6.52 once we came back tube felt a little low on air. The heat stretches the material like crazy.

 

[Chopperbill]

I hauled it with my flat bed aluminum trailer and it bounced like a basket ball on the keel even tied down. I know the keel is much softer than the rest of the boat. Could be part of the problem. Hate to drill my motor for the hydra foil if I can fix it some other way, however, Saturn recommends hydro foils.

 

[Guest]

Forget about what saturn recommends. Talk to Sinister he has the same boat. He does 20mph solo on his 15. Your 9.8 with 2 people and a dog should do about 10-14mph.

 

[Sea Rider]

Don't overfill , + 6 PSI is a real exaggeration, could blow tubes seams. Usually factory pressure tests between 5-7 PSI for 48 hours. Know some Italians builders that does so to 15 PSI, but those tests are for heavy duty Hypalon inflatables. Is your 9.8 engine achieving a correct transom height while sitting on that transom ? Tohatsu has sitting issues, have bit larger lower units compared to other brands.

Happy Boating

 

[Chopperbill]

Water runs just below deflection plate. No water is thrown back in boat and very little behind boat. I can raise it about 3/4 an inch then run out of transom. Some of my problem is I am running 5000 feet altitude. My Harley runs like it had twice the HP in AZ at 300 feet. Figured I would gain more power on the boat where we will use it the most.

 

[Sinistre1]

You should definitely be able to plane with all but the most anemic of 9.8's.... something is amiss. Weimed could plane out with a long shaft 6hp on a similar sized boat. I have come very close to planing with a 2.5 on a Mercury Quicksilver 340.. if I rode a wave just right the boat would start to climb and fall off (the sign it is about to transition to planing but the action of falling back into the water slowed it down and knocked it off the transition hump. You should def be able to plane. The altitude thing has an effect... maybe even a large one but you have enough hp that losing 40% should still leave you with reserves... at least one up!

 

[Sea Rider]

Water runs just below deflection plate. No water is thrown back in boat and very little behind boat. I can raise it about 3/4 an inch then run out of transom. Some of my problem is I am running 5000 feet altitude. My Harley runs like it had twice the HP in AZ at 300 feet. Figured I would gain more power on the boat where we will use it the most.

Which plate do you mean by deflection plate, The small upper one or the larger bottom one. Ideal is for water flow to skim right under small upper one. Is there were you have matched water flow to pass by ? Air decks sibs must be top inflated to perform as expected, take your pump along with you when outing and top back the entire sib once floating at rest for some minutes por pressure to stabilize, With a 9.8 you are underpowered to plane with heavier loads, worst at "altitude" as opposed to sea level. You're losing about 30% of power at 5K ft height of elevation, so literally running with a 7.5 HP.

If you will be sibbing constantly at that altitude, there are market available high altitude jets for given height altitudes, if not mistaken in 1K meter increments. Engine will work better, for maximizing engine will need a less prop pitch to compensate power loss. That must be done with a induction tack and wot test once jets are changed. If not will need to live achieving only fast displacements boring speeds.

Happy Boating

 

[Guest]

@searider, My last outing which was Sunday was pumped to 45kpa which equal to 6psi. I do not recommend Bill to do this but Sinister and myself inflated to 45kpa. Boat rake great. I never knew altitude had effect like that. Well learn something new every day

 

[Chopperbill]

Which plate do you mean by deflection plate, The small upper one or the larger bottom one. Ideal is for water flow to skim right under small upper one. Is there were you have matched water flow to pass by ? Air decks sibs must be top inflated to perform as expected, take your pump along with you when outing and top back the entire sib once floating at rest for some minutes por pressure to stabilize, With a 9.8 you are underpowered to plane with heavier loads, worst at "altitude" as opposed to sea level. You're losing about 30% of power at 5K ft height of elevation, so literally running with a 7.5 HP. If you will be sibbing constantly at that altitude, there are market available high altitude jets for given height altitudes, if not mistaken in 1K meter increments. Engine will work better, for maximizing engine will need a less prop pitch to compensate power loss. That must be done with a induction tack and wot test once jets are changed. If not will need to live achieving only fast displacements boring speeds. Happy Boating

Starting at the bottom you have an AV plate, then a small plate by the water plug and lower unit oil level plug, then a larger plate above it. The top plate is what I thought was called the deflection plate to keep water from running up the drive unit. I put a 3/4 inch shim under the motor and the AV plate is now about 1 1/2 inch below the keel, that's as far as I can go.

 

[fbpooler]

At 5,000 ft elevation, you need special jets and even with that you will not get rated horsepower. The less dense air contains less oxygen than air at sea level thus the jets are probably smaller.

You cannot compare engines run at that large a difference in elevation, A friend has a light aircraft which is fine at lower altitudes but struggles above 5,000 ft.

 

[fbpooler]

At 5,000 ft elevation, you need special jets and even with that you will not get rated horsepower. The less dense air contains less oxygen than air at sea level thus the jets are probably smaller.

You cannot compare engines run with that large a difference in elevation, A friend has a light aircraft which is fine at lower altitudes but struggles above 5,000 ft.

 

[Sea Rider]

Some tech issues to consider :

To take the most out of your particular 365-9.8 HP setup you need 2 issues to consider that works hand in hand, transom height and engine power. To start with, engine must be seated at 90 angle on transom, or perpendicular to water level once sib is floating empty. Adjust trim to achieve that condition.

So you have placed a wooden shim to raise engine as you probably were experiencing water splashes over engine, right ? If so, you need to correct dial the Sweet transom height spot for that Tohatsu engine. You can only have 2 possible heights for water flow to pass by at plane.

Right under small water deflector plate (WDP) and above anti ventilation plate (AVP). Do not have it clear where is your actual water flow is passing by ?

Sit on middle deck next to transom, go for a wot spin you alone on flat calm, no wind water, first hour of day could be best, once on plane, pull your head over next to engine side and check at which height is flow passing by. Check pics (if visible)

First corresponds to WDP, second to AVP. Shim transom +,- to achieve that first condition. If water flow is passing right in middle of both, it is much better than just passing by second, but 1 is top performer. More water bed level for prop to bite & grip better than in 2.

Once you have it correctly dialed, could make a permanent shim installation, and rise both engine plates to be even with newly raised transom border, that way when adjusting engine, both engine clamps will be adjusted around middle plate.

With respect to elevation issues, the power loss is around 20% at each 1K meters (3300 Ft) There are market available high altitude kits in 1K increments, max is around 3K Ft. At only 5K Ft, playing with jets and prop pitch should be able to squeeze the near top HP out of that 9.8. Other story is passing 10 K Ft and higher.

Happy Boating

 

[Sea Rider]

Don't understand at all what is being done while "Sorry the site is under maintenance" no pics shown, Let's try again







Happy Boating

 

[Chopperbill]

No Title

These two plates are above the AV plate. The owners manual has no description of these plates. The water is running just under the top plate. I am just guessing it is called the deflection plate. I raised the motor as far as i could so I can get the AV plate to ride closer to the surface. Most of our boating will be done in Arizona at sea leaval so I really don't want to make too many changes to carb or prop if it is not necessary.

 

[Chopperbill]

No Title

Mine aren't showing either.

 

[Chopperbill]

There it is ^

 

[fbpooler]

If you leave the low altitude jets in place, the engine will run rich at altitude due to less oxygen being available. If you put high altitude jets in, the engine will run lean at sea level which is the worst possible thing to do. How often you use it at high altitude would be the measuring stick for you.