1977 Starcraft 14' Holiday Restoration has officially begun

[MichaelP]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

Lower both trim tabs a bit, equally. Or shift weight forward. Or lower the OB thrust pin 1 more hole. I would try these in that order. Once you get the boat under control and running at max rpm then consider playing with props.

 

[chrisp929]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

Gas tank is forward, im forward, all movable weight forward, tried manual tilt at lowest and second to lowest setting with similar results. I dont know speed but i will check with gps. And i have no clue about rpms. I dont have rpm guage. Battery and oil tank are only things in the rear of the boat. All weight is forward.
Maybe ill just try a hydrofoil. Is there any brand that doesnt require drilling into cav plate ?

 

[yooperangler]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

I think getting a speed reading should be first at this point if your going 40 50 60 even high 30's little waves and swells can cause some pretty good banging on most boats. Also curious how fast its going now to see if you need to fine tune this for more speed or adjust prop size for engine performance. I guess it depends on how fast you wanna go

 

[chrisp929]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

I gps'd my speed. I plane at like 14 and cant get more than 18 before i have to stop or ill bash the boat apart from the porpoising. Somethimes if the water is glass smooth and i accelerate veeery slowly, i can hit faster speeds but as soon as i hit a small rogue wave, the porpoising starts and the fun is over. I double checked and the cav plate is even with bottom of boat. Im worried that im gumming up the engine. 2 strokes like to run at wide open throttle to burn the fowling off the plugs. I need to fix this.

Dang nabbit

 

[yooperangler]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

Was the boat porpoising like this on the first run ?
"So i splashed the boat this weekend twice. It flys .. but within the first 30 minutes i ran up in some shallows and wacked my skeg before i could slow down enough to stop"
Is it possible you did damage to anything other than the skeg? I see in another post you said something about hammering a dent out of the prop? Only reason I'm asking is 18 mph isn't very fast to be getting major control problems I agree that you need to get the rpm's higher on the motor that can be fixed with the right prop and if the one you have is damaged probably best to replace anyway. I'm just wondering if the porpoising started after the skeg wacking if the problem isn't the result of a bent blade rather than wrong pitch prop ?

 

[chrisp929]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

Was the boat porpoising like this on the first run ?
"So i splashed the boat this weekend twice. It flys .. but within the first 30 minutes i ran up in some shallows and wacked my skeg before i could slow down enough to stop"
Is it possible you did damage to anything other than the skeg? I see in another post you said something about hammering a dent out of the prop? Only reason I'm asking is 18 mph isn't very fast to be getting major control problems I agree that you need to get the rpm's higher on the motor that can be fixed with the right prop and if the one you have is damaged probably best to replace anyway. I'm just wondering if the porpoising started after the skeg wacking if the problem isn't the result of a bent blade rather than wrong pitch prop ?

My first run included my girlfriends brother .. who is about 160 lbs and me at 240. The both of us were sitting in the front .. I seem to have been able to get to hi 20's or low 30's with the 2 of us in the boat. It was still porpoising with us just not as bad.

When i'm in the boat alone, i have my cooler up front, and i move the gas tank up front, and it still doesnt seem to be enough to get the same speed as with 2 adults on board .. The porpoising is worse when im alone ..
There isnt anything else to move forward. I'm at a loss. Just myself alone at 240 lbs should be enough considering this is a tiny little 14 footer. This isnt some cabin cruiser. It's basically a glorified canoe with a windshield, cuddy, and engine ..

I straitened out the skeg with a big crecent wrench. It's almost new now. And the prop only had a tiny ding in it which i lightly hammered out and now its back to new. It was a very very small dent. The only reason i even bothered to hammer it out is becuase i took the prop off just to take it off for a first time experience, and i greased the splines as well .. so since i had the prop off, and i was close to my vice/anvil, i grabbed my body hammer and very very carefuly tapped out a small ding in the prop.

Nothing has really changed on the boat. Should i try one of those wedges ? And if so, should a get a negative wedge, or positive wedge ? They come in 1-5 degrees ..

 

[ezmobee]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

You don't have a long shaft motor on a short transom do you?

 

[yooperangler]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

You don't have a long shaft motor on a short transom do you?

This? Or the opposite ? Not trying to steer you away from hydrofoils and props and such just sounds like a pretty significant control problem at relatively low speeds and I think of those things as more fine tuning for best performance at optimum speeds, WOT etc.. Post some pics of the stern with motor etc... Its possible you just have way to much prop on there and may want a different prop ,hydrofoil ,or may find you need tnt to get the performance you want but lets eliminate the obvious first. Also you said you have manual trim tabs did you trying lowering them like MP suggested ? Also get those numbers off prop lets see if we can figure out whats on there now. Just trying to get the big picture so we can troubleshoot this and hopefully avoid buying multiple props etc...

 

[chrisp929]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

This? Or the opposite ? Not trying to steer you away from hydrofoils and props and such just sounds like a pretty significant control problem at relatively low speeds and I think of those things as more fine tuning for best performance at optimum speeds, WOT etc.. Post some pics of the stern with motor etc... Its possible you just have way to much prop on there and may want a different prop ,hydrofoil ,or may find you need tnt to get the performance you want but lets eliminate the obvious first. Also you said you have manual trim tabs did you trying lowering them like MP suggested ? Also get those numbers off prop lets see if we can figure out whats on there now. Just trying to get the big picture so we can troubleshoot this and hopefully avoid buying multiple props etc...

No the transom is a 20 inch transom and the engine is a long shaft .. the cav plate is exactly even with the bottom of the boat .. i will certainly post pics later anyways ..
the trim tab i refered to was for countersteering .. not the tabs on the back of the boat .. the little doohicky you adjust so your steering doesnt pull to the left or right ..

 

[chrisp929]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

So here we are ...

Directly from the back of the boat .. i think this pic still had outboard in second to last tilt adjustment hole ..

right side ..

left side with flat steel bar to show that cavitation plate is within half inch of bottom of boat .. the last few inches of the stern of the boat roll up a little, so if you take that into account, then the cav plate is close to even with the bottom of boat ..

top cyclinder plug .. fowled up kinda because i cant open up wide on the throttle . and i was also putting around waiting at the dock to take boat back out yesterday so thats not good for 2 stokes either .. just idling ..

bottom cyclinder plug .. little cleaner .

I'm leaning heavily on buying these wedges ..

they sell them here on iboats .. they fit between my transom and outboard .. they are fatter on top, and more skinny on the bottom. So the cav plate should have a slight incline at the front, and decline at the rear .. in turn acting as a further tilt, and allowing JUST a TINY bit little more water to come under the cav plate than over, creating a touch of rearward lift .. hopefully stopping my porpoising ..

i feel that when under way, as im cruising, the cav plate may have a slight decline in the front .. in essence 'digging' into the water and bringing the outboard down and bow up .. this is more present when the boat is light up front such as when im alone, or when i hit a wave, and the wave sends the front end of the boat upwards .. in turn begining the 'digging' of the cave plate and sending me on my bouncy bounce ride ..

is my theory sound ?

 

[chrisp929]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

Does this make sense .. the orange is the outboards pivot point ( roughly ok ), the green is the new angle of the cav plate after wedges installed, and the blue arrow is the water now hitting the bottom rearward portion of the cav plate, inturn pushing the bow of the boat down, reducing or eliminating bow rise and porpoising ..

my hypothesis .. what do you guys think ?

 

[chrisp929]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

I just googled transom wedges and i found this quote on another forum ..

Put a 2x4 up against the bottom of the boat, slide it till it hits the lower unit, the "top" of the 2x4 should be approx 1/2-3/4" below the bottom of the anti vent plate.

I really think the engine is sitting to low on the boat.

I also read online that some guys raise their outboards up 1 hole and porpoising is reduced noticeably.

opinions ?

 

[ezmobee]

Re: 1977 Starcraft 14' Holiday Restoration has officially begun

First try raising it just a little above the keel and see what happens.