Stringer repair

[bjf66]

Turbo exhaust riser
a few monthsago I started fabricating up stainless riser thinking I knew what i wanted to do
Used 3" sch10 stainless elbow and pipe, had all the hard work done....then had a rethink on what was trying to achieve. and decided to scrap this idea and try and utilise the 30 degree water cooled powerflow plus risers that I already had

the fabrication came out okay .....seems a shame to scrap them as few hours in them, Oh well got some welding practice in

 

[bjf66]

after arriving at the conclusion to scrap the fabricated S/S risers. decided to have another closer look at what could be done with the Imco water cooled 30 degree risers i had here.
Looked at shortening them, however after reviewing this, decided to utilize as much of the water cooling manifold as I could, and move the turbos around to make them fit, and at least retain 14 degree angle on the double water cooled pipes from turbo to transom, and to get approx. 4" tail pipe out of the back end of transom
The 4" double skinned turbo pipes are all dry until the very end of the transom, and 14 degrees angle should help deter water coming back up pipe from transom....hopefully

used sch10 stainless pipe 3" to 4" to connect with aluminium risers
may have to make some support brackets to take some of the weight off turbos

 

[Baylinerchuck]

Just curious if you lose much performance not having sweeping turns in the exhaust exiting the manifolds? I definitely don’t have any performance boat experience and I reckon it’s a nightmare trying to squeeze turbos in that tight space. Love the updates.

 

[Scott Danforth]

I would loose the sweeping elbows off the imco's, make a spacer mount and mount the turbos directly on top, less plumbing for both the intake and exhaust side.

 

[bjf66]

from what i have read the turbos like a little turbulence prior to turbo, which is different to natural aspirated engine

the riser pipes are large and then reduce down from 4" to 3" and then 3.5" out of the turbos back to transom

need to incorporate 2 blow off valves into pipes as well

 

[Scott Danforth]

the elbows will straighten the flow and reduce turbulence to the wheel.

 

[bjf66]

this seems an interesting article comparing back pressure relative to exhaust size leaving turbo, using standard exhaust manifolds


https://www.enginelabs.com/engine-t...-got-back-turbo-exhaust-size-comparison-test/

 

[bjf66]

managed to get the turbo pipes all tacked up, and managed to get hold of local welder to tig weld the pipes, they look neater than the arc welder.
I need to find some time to practice on the tig welder I have here, haven't mastered the skill yet.

still pondering what size and type of waste gate to be used on pipes. Looking for a water cooled 38mm * 2 waste gates, don't think I need to go bigger than this this as turbos are not that large
Then need to get the wastegate pipes welded into the collector and route the wategate exhaust pipes to exit outside of the engine hatch

 

[bjf66]

so exhaust getting to finishing stage and will be ready to pull engine after this is finalised, and then can start to turn attention to finishing the hull

 

[bjf66]

Re: Trim Tabs
whether to run them or not??
The boat is 21' long x 7.4' across rear deck
Have 2 sets of mercury S280 (14"x19") K-Planes (one set complete ) with plates that are straight and another set of plates which are angled and need a clean up

Then a set of trim tabs which came with boat when I purchased the hull. originally this hull was set up with large outboard, dont know who built it, never seen any pictures of the boat running in water, cant find anyone that knows anything about the boat, perhaps I'm not mixing in the right circles as it originally it came from far north Queensland, and I'm in south

These trim tabs are huge, 28" wide x 16" long, mire like a large cav-plate and follow the planked contour of the hull

Now for the dilemma:
1. to run either of the K-planes which need 12" clearance from base of transom to top of plate, however would need to massage the transom to be able to mount the transom plate...at this stage this is possible, just a little more work ...however easier to do this now prior to finishing the hull

2. run the large trim tabs which came with hull, this can operate within the confined height as mounting holes are still in place on lower transom, they will need to modified slightly on inside of plate as the transom steps out where the arneson drive is bolted up to.
This plate has aggressive planking design which follow contour of the hull, 28" wide x 16" long
would need to mould the trim cylinders onto the hull, whether I use the mercury cylinder or other hydraulic cylinders, or look at electric or self levelling trim cylinders

I have no experience with any of these setup and feeling like I'm out of depth

However a little work now to prep the transom will be easier than trying to do this latter

I've attached a few pictures and grouped them together with the K-plane or trim tab plates

any ideas would be helpful!!!!!

 

[bjf66]

Re: large trim tabs aggressive planking following contour of hull

 

[bjf66]

the trim tab plate is sitting on angle as inside of the plate is hitting the transom where anerson is bolted, and will need some remedial work to mount the plate flush
However this plate mounts quite low through having just a hinge and no backing plate

lets hear from some experts?

 

[Scott Danforth]

Less work to run the ones that came with the hull

 

[bjf66]

scott
you dont think these plates are too large
the starboard trim cylinder mounting point would be close to the arneson steering arm, may need to come mount the T/T cylinders away from the transom some how
not sure whether can get custom mounting brackets ....or have to end up making them

Yes installing the K-planes would be more fibreglass work as far as grafting the transom to bolt the flat transom plates , however they would be well under the arneson steering arm, and wouldn't pose any interference

 

[bjf66]

turbo pipes fitted up

 

[Scott Danforth]

scott
you dont think these plates are too large
the starboard trim cylinder mounting point would be close to the arneson steering arm, may need to come mount the T/T cylinders away from the transom some how
not sure whether can get custom mounting brackets ....or have to end up making them

Yes installing the K-planes would be more fibreglass work as far as grafting the transom to bolt the flat transom plates , however they would be well under the arneson steering arm, and wouldn't pose any interference

you may want the extra running surface with the weight of a big block in the back of such a small boat. however the K-planes would be fine too

 

[bjf66]

spoke to a few contacts who have played with surface drive in much larger boats and the feeling is maybe I dont need the trim tabs as you get some lift in rear with surface drive

I'm concerned if I go with the larger 24"x16" tabs they will give too much lift too the transom, I did cut off the inside edge of tab plate to make clearance, and turns out the tabs are made of balsa as core

The hydraulic actuators would need to be off set slightly to get the pump central and away from the Arneson steering cylinder

 

[bjf66]

Therefore had another look at the K-planes in weekend and mocked up location close running horisontal with transom dead rise, and seem to work in better with location, and the actuator transom mounting bracket

The K-planes 280S (14" x19") backing plates will have to be cut down considerably, and won be using the top actuator mounting on transom plate, I'll be just using the backing plate to mount the K-plane with pivot hinge

The used actuators seem okay although haven't tested them yet, however they have suction if if you place finger over the hose

Took the K-Planes apart
There is corrosion on one backing plate near top section of plate however proposing to cut this part off as need to reduce the height of backing plate to make them fit

had to cut one of the pivot pins off to separate plates, have order 316 Stainless steel 1/2" Dix x 16" long and will die nut to cut the 1/2" x 20 unf thread in weekend
have order 2* new sacrificial anodes for plates
they need to be sandblasted, filled, and under coated
need to organise new bushings and washer for the actuator tab plate as had to cut the rubber bushing off to separate actuators

The plates shown in picture on starboard side is the actual plate for port
Therefore will settle on using the K-Planes S280

 

[bjf66]

will most probably just as easy to fabricate the actuator brackets out of 316 stainless plate, 3/8" plate have them polished and then welded
started to make some templates
hopefully the K-Plane studs with internal hole / thread for hydraulic fluid can be relocated into new position on transom

 

[bjf66]

After unsuccessfully tracking down the owner of the boat that was purchased some 4 yrs ago, I decided as a last minute reaction to join facebook with the few to making a posting seeing if someone could help
well my luck and the power of social media was able to find the contact who used to ski behind the boat in last 80s-early 90's when it had a Johnson V8 pushing it along.
Gary was able to help me out and send 2 older photos with Predator offshore skiing off Mission Beach in Far North Queensland.
Have also managed to track down the boat designer and builder who is in the USA building pools. Crazy stuff considering I looked high and low when I purchased the boat to find someone who knew something about the old girl
Gary mention in 1-2 ft chop they were skiing around 70mph offshore
Trying to get more details
at least 2 photos this week are better than none that I had the week before