I/O (Sterndrive) Conversion to Outboards

[redneck joe]

So I've seen the fiberglass numbers for years, what do they (and csm) mean

 

[tpenfield]

I got the 5 gallon pail of VE resin, but the delivery person must be holding my 1708 cloth hostage or something. Awaiting a ransom letter. . .

Meanwhile . . . I have taken a look at the transom. Flatness, height, bolt positions, etc.
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Flatness: I am thinking that I could use the cut-out pieces of Coosa from the transom along with some fiberglass putty to make/form a flat area (red dotted line)

Transom/Engine Height: By my best measure . . . the top of transom is 30.5" above the planing surface at the mounting point of the outboards. The spec. of the shaft length is 30.1" . . . making the ventilation plate a wee bit (0.4") above the water stream. There is a 'rule of thumb' when extending the outboard on a bracket . . . 1" of engine height for every foot of bracket extension. I asked about the science behind this 'rule of thumb' on another forum and a bar-room brawl ensued.

My splashwell bases block the lower position on the top series of holes. That should not be a problem, as the upper holes are what matters. FYI - The BF350 gets 2 top bolts on each side (i.e. 4 bolts) and then 2 lower bolts in the slotted area.

In my on-water testing after 'splash day', if it looks like I need to raise the engine, I can probably get 0.5-1.0" inch without any problem.

 

[redneck joe]

Thats a lot of math.


How can one adjust after the holes are drilled?

 

[alldodge]

Thats a lot of math.


How can one adjust after the holes are drilled?

Silicone can fix everything

 

[alldodge]

I got the 5 gallon pail of VE resin, but the delivery person must be holding my 1708 cloth hostage or something. Awaiting a ransom letter. . .

Meanwhile . . . I have taken a look at the transom. Flatness, height, bolt positions, etc.
.
View attachment 415305
.
Flatness: I am thinking that I could use the cut-out pieces of Coosa from the transom along with some fiberglass putty to make/form a flat area (red dotted line)

Transom/Engine Height: By my best measure . . . the top of transom is 30.5" above the planing surface at the mounting point of the outboards. The spec. of the shaft length is 30.1" . . . making the ventilation plate a wee bit (0.4") above the water stream. There is a 'rule of thumb' when extending the outboard on a bracket . . . 1" of engine height for every foot of bracket extension. I asked about the science behind this 'rule of thumb' on another forum and a bar-room brawl ensued.

My splashwell bases block the lower position on the top series of holes. That should not be a problem, as the upper holes are what matters. FYI - The BF350 gets 2 top bolts on each side (i.e. 4 bolts) and then 2 lower bolts in the slotted area.

In my on-water testing after 'splash day', if it looks like I need to raise the engine, I can probably get 0.5-1.0" inch without any problem.

Maybe discuss with NA but I'm thinking the drive height might benefit higher

Why

Using Crap----erall insight, they have the motor height higher than bottom of hull. The forward power is good, reverse not so much. The motors are set back further so water will come up prior to making contact

 

[Pmt133]

I watched a guy from bluewater talking about mounting height, he was saying every 10 inches back from the end of the running surface they move them up an inch or so as a "rule of thumb" Since the running surface is being extended here, they may not end up being "up" all that much.

I'd imagine you want the AV plate around the surface. My drive is completely buried at wot but I can't easily fix that... tis a wee bit more difficult with an I/O.

 

[tpenfield]

Thats a lot of math.


How can one adjust after the holes are drilled?

The bolts stay where they are. The engine gets moved up to another set of holes. That’s how engine mounts work.

 

[redneck joe]

Ah, forgot about that. I've only mounted one outboard.


And side note, my seemingly stupid questions are all asked thru ignorance (or as in the above forgetfullness) but as with all my life I've always been the one to ask rather than pretend im cool and all that sh.t so others don't feel stupid for asking questions.

This thread is highly technical and I will retain about 5% of what I read here but others may gain more than me. My first post on a boat forum in 2005 or so was about a bayliner boat on tht. I was roasted without mercy. After my initial embarrassment I decided to be the one to ask stupid questions so others did not have to feel what I felt 20 years ago.

So, answer my stupid questions.

 

[Pmt133]

Ah, forgot about that. I've only mounted one outboard.


And side note, my seemingly stupid questions are all asked thru ignorance (or as in the above forgetfullness) but as with all my life I've always been the one to ask rather than pretend im cool and all that sh.t so others don't feel stupid for asking questions.

This thread is highly technical and I will retain about 5% of what I read here but others may gain more than me. My first post on a boat forum in 2005 or so was about a bayliner boat on tht. I was roasted without mercy. After my initial embarrassment I decided to be the one to ask stupid questions so others did not have to feel what I felt 20 years ago.

So, answer my stupid questions.

There's no stupid questions sir. The dumbest are simply the ones never asked.

Went through this at work a few weeks ago. I'm not an electrician by any means but ours rewired a VFD cabinet and we were not getting any control of the VFD through the system. He starts ripping apart his wiring thinking he wired it wrong and I just go "what if it isn't wired wrong but rather the loop for the data isn't complete and its only doing what it can do not what its told to do." Sounded dumb at the time but came to find out the next afternoon that there were a set of latching relays for the soft start (not documented of course) that also completed the signal loop and were preventing it from relaying the run signal. Simple repin of 1 wire was all it took. And then I felt pretty good I was on the right track that it was just doing what it was told.

 

[Scott Danforth]

Ted, I think you are making the flatness harder than it has to be. Think body work or drywall work or concrete work. Large flat knife or spreader to spread the PB. While wet, use a 2x4 and float the surface.

Smooth out with the spreader. As it starts to kick, hit with a large flat-board sander with 40 grit. (Because sanding reinforced PB after it cures is like sanding concrete)

Then go back and hit with 80 grit

 

[tpenfield]

Ted, I think you are making the flatness harder than it has to be. Think body work or drywall work or concrete work. Large flat knife or spreader to spread the PB. While wet, use a 2x4 and float the surface.

Smooth out with the spreader. As it starts to kick, hit with a large flat-board sander with 40 grit. (Because sanding reinforced PB after it cures is like sanding concrete)

Then go back and hit with 80 grit

Yes, I'll probably combine a few methods 'a La' drywall smoothing. Often when doing stuff that is non-textbook, I see what is working and adjust accordingly.

In other news . . . the 'ransom note' on my 1708 shipment (or lack thereof) has been posted on the delivery status

"Your package is delayed because it was misrouted. We've successfully rerouted it and it's now on its way."

It is only when I need something quickly do the shipments get delayed.

 

[redneck joe]

Had a buddy tracking some parts for his rv that got 'delivered' to the same facility a few times every day for 16 days.

 

[Pmt133]

Fedex still has a gear of mine out for delivery... been that way for 6 years.

 

[redneck joe]

Ok so slight derail of thread but per my recent post let me know if I need this kind of education.

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[redneck joe]

Still waiting on answer for all the numbers question.


I think pb is peanut butter of course reference epoxy mixed with chopped strand of some number fiberglass.

 

[Pmt133]

Still waiting on answer for all the numbers question.


I think pb is peanut butter of course reference epoxy mixed with chopped strand of some number fiberglass.

Sorry, 1708 for example is 17 oz biaxial cloth stitched to 3/4 ounce csm. 1808 is 18 ounce and so on. CSM is chopped strand mat and is sold by weight.

 

[tpenfield]

So I've seen the fiberglass numbers for years, what do they (and csm) mean

This question . . . ?
1708 according to AI . . .

1708 fiberglass is a high-performance reinforcement fabric consisting of a 17 oz per sq yd biaxial fabric stitched to a 3/4 oz per sq ft (approx. 8 oz/sq yd) Chopped Strand Mat (CSM) backing. The total weight is roughly 25 oz per sq yd.

. . . thus the designation of '1708' First 2 digits are the weight (oz./Sq. yd.) of the top side, and the second 2 digits are the weight of the binding (bottom) side.

1808 being similar, but slightly heavier top side

2415 being even heavier on both sides.

You might also see the prefix 'DBM' with the numbers, which signifies 'Double Bias Mat'. Which means it has 2 layers of strands that run in opposite directions (usually 90˚).

1708 has the fibers running at -45˚ and +45˚ to the 'direction' of the cloth (direction being the way the cloth comes off the roll).

1808 has the fibers running in the direction of the cloth (0˚) and across (90˚) the cloth. (as does 2415.)

 

[tpenfield]

Speaking of fiberglass cloth and such . . .

I did a cross-check of my fiberglass usage vs how much Coosa board used to build the extension bracket (probably should have done this day 1 )

6pcs x 48"x96" x 2 sides x 80% utilization = 44,236 sq. in. of Coosa to cover with fiberglass (24.5 linear yards)

In total, I have used 79 linear yards (50" width) of fiberglass cloth.
79yd x 36in/yd x 50" width = 142,200 sq. in of cloth

Which results in an average of 3.2 layers per side of Coosa.

Hindsight - 20/20 vision . . .

 

[redneck joe]

So the number is like a thread count on a bed sheet and csm is chopped up stuff then sewn into a sandwich of (insert number here) of a full sheet of not chopped up woven fabric?

 

[tpenfield]

The DBM 1708 arrived . . .
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I was able to form the port splashwell . . .
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Tomorrow I will see about adding some layers to them.