I/O (Sterndrive) Conversion to Outboards

[tpenfield]

1 transom cavity filled with 1" of fiberglass . . . 1 more to go.



22 total layers of 1708,1808, CSM combination . . . 1 gallon of resin.

 

[flashback]

Getting pretty heavy eh..

 

[tpenfield]

For those contemplating making a thick plate of fiberglass as I am doing . . . Don't

My method has been to lay up CSM & 1708/1808 in alternating layers. I was originally thinking about 22 +/- layers. When I get to 3/4" of build-up, I place some plastic sheeting over the fiberglass in the cavity and use the 1" Coosa piece that I cut out as a 'tamp' and apply some weight to flatten the fiberglass out, so that it is even. Here is a picture of the cavity filled to 3/4" , 'flattened', and cured. . . . It has about 1/4" more to go to be level with the surrounding Coosa.

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Since my shop is fairly cold for fiberglassing (60˚F), it takes a while for the resin to 'kick' . . . but once it does . . . holy cow . . . quite a bit of exotherm !
The piece gets up to about 120-130˚F.

After curing, I add more layers of fiberglass to get up to the 1" thick. What I am finding is that I need about 25-26 layers of glass to get to the 1" . . . probably because of the CSM layer is not as thick as the 1708 and 1808 layers.

I hope to be done today with the inserts and then moving on to the next thing . . . which may be glassing in of the planing surface.

 

[Scott Danforth]

Hey Ted, Mercury is showing the new 808 hp outboard at Miami. you could get by with one motor.

 

[alldodge]

Hey Ted, Mercury is showing the new 808 hp outboard at Miami. you could get by with one motor.

and loose the joy-stick, ohhhh no

 

[Pmt133]

Hey Ted, Mercury is showing the new 808 hp outboard at Miami. you could get by with one motor.

Yeah... but I'd still want twins.

 

[flashback]

1600+ hp, that would be sweet!

 

[Scott Danforth]

1600+ hp, that would be sweet!

Ted may be currently contemplating another layer or so of fiberglass......

 

[tpenfield]

Hey Ted, Mercury is showing the new 808 hp outboard at Miami. you could get by with one motor.

perfect

 

[tpenfield]

Getting pretty heavy eh..

Yes . . . But all for a good cause

My latest estimates, based on the recent changes are

Bracket ~ 500 lbs.

Hull Modifications/bracing ~ 200 lbs

Very little weight reduction overall . . . about 200 lbs.

 

[Scott Danforth]

Ted, how many cases of beer will fit in the bilge where the two 6.2's used to sit?

Did you figure in the weight of "provisionings" in your calculation?

 

[tpenfield]

I got the transom inserts done . . .

Here is a picture of the process . . . rolling out each layer to ensure that there are no air pockets. I add the resin (~ 5 oz. ) for each layer and then lay the cloth on top of it so the resin soaks upward into the cloth (or mat), forcing the air out.

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It is a tedious process, but it works. I calculated the glass-to-resin ratio using a volume calculation. Each cavity is 275 cubic inches and I used a gallon of resin (230 cu. in) on each. So, the glass content is about 16% by volume. It seems pretty low, even though I painstakingly rolled the glass to force the resin up from the layers below.

Here is the transom with both inserts glassed.

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[alldodge]

Looks good, did ya ever think about aluminum plate or honeycomb aluminum plate?

 

[tpenfield]

Looks good, did ya ever think about aluminum plate or honeycomb aluminum plate?

No, because of temperature coefficients of aluminum vs fiberglass, foam, etc.

 

[tphoyt]

I learned about that hard way as a kid. I glassed over an aluminum plate and it delaminated in the first winter and I was living in Fl at the time. To much movement between the 2 different materials from the temp change.