I/O (Sterndrive) Conversion to Outboards

[Pmt133]

Wow . . . you would think they would put their best foot forward. I did talk to someone about a pair of used Suzukis (2021). Both gear cases have been replaced under warranty/recall sort of issues.

I think it is all a crap shoot as to how reliable the engines are (or not).

I agree. Much like anything else at this point you're rolling the dice. It's been 10 years since I've even been to a show so it was nice to check it out again.

I will say I sat down with a formula rep looking at the 33... had twin 400s on the back. He ran them with the older triple setups then with the twins and said the current mercs, even in the twin setup down on power a little, are really impressive. I obviously don't have formula money... but a guy can dream.

 

[tpenfield]

This is what's happening for the engines . . .
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Honda BF350's AUDA/AUCDA
Optimus 360 Joystick system

They are big, but rarely has it ever been recommended to get a smaller engine when it comes to boats . . .

I just got back from the re-power shop, having placed the order. With the sales incentive, it puts me back in-line with my original budget .

 

[Lou C]

Very nice Ted, 700 hp! And less weight!

 

[tpenfield]

Very nice Ted, 700 hp! And less weight!

Actually these engines are heavy, so the overall weight will come out about the same.

The Suzuki 350 HP would have been 747lbs, the Mercury 350's would have been 720lbs. These Hondas are 776lbs. (each)

 

[Pmt133]

Thought the mercs were under 700... or did they exaggerate a wee bit?

 

[Lou C]

Interesting, so about the same weight as (engine alone) a Mercruiser V8, but then you have to add the transom mount/outdrive and you know how heavy Bravos are lol.

 

[alldodge]

So decided to go with the weight equivalent of the V10 instead of V8

 

[Scott Danforth]

Actually these engines are heavy, so the overall weight will come out about the same.

The Suzuki 350 HP would have been 747lbs, the Mercury 350's would have been 720lbs. These Hondas are 776lbs. (each)

so...... you have to leave 1 case of beer behind? or did you account for that in the buoyancy calculations

 

[tphoyt]

Being back on budget must feel real nice.
I can’t say I have ever heard anyone say anything bad about Hondas. I had a 15 back in the 80’s and it was bullet proof and never let me down. They are heavy but in my eyes that usually means better built.
Congratulations

 

[tpenfield]

so...... you have to leave 1 case of beer behind? or did you account for that in the buoyancy calculations

Yes, there is about 2,000 lbs of buoyancy in the extension-bracket. Per the analysis the N.A. did, the hull sits with a very slight positive trim. Between the extra weight of the engines and gear ( I mean beer ), the boat should be around 1˚ positive trim.

 

[tpenfield]

Thought the mercs were under 700... or did they exaggerate a wee bit?

To get 350 HP, you have to go to the V10 . . . Top of the V8 line (600 ish lbs) is 300 HP.

 

[tpenfield]

Being back on budget must feel real nice.
I can’t say I have ever heard anyone say anything bad about Hondas. I had a 15 back in the 80’s and it was bullet proof and never let me down. They are heavy but in my eyes that usually means better built.
Congratulations

Yes, excited about the budget fix . . . I also saved $1,900 by ordering silver instead of white.

 

[Pmt133]

To get 350 HP, you have to go to the V10 . . . Top of the V8 line (600 ish lbs) is 300 HP.

I had to double check the brochure for the mercs I got from the show but it matches their site, quotes 695 for the V10 with the big gearcase...

And regardless we're talking a total weight difference of what~120lbs. Pretty insignificant in the grand scheme of things anyway.

 

[tphoyt]

It’s pretty wild there is that much of a difference in cost over the color.

 

[tpenfield]

The Honda BF350 'U' (30") shaft motors weigh about 775 lbs. My design calculations were based on 700 lbs/engine. Out of curiosity, I ran the force calculations again using 800 lbs as the engine weight. Forces from engine thrust were already figured using a 350HP engine.

Not to bore folks with the details, but the force on the structure from both weight and engine thrust with safety factors applied increases by 6% . . . Localized forces on the transom will be about 2% higher than previously calculated.

Much of the force on the transom is a result of the engine thrust, and I had already used a thrust based on 350HP . . . So, no worries.

In other news . . .
I have attached the running surface and flipped the extension pod over (which was no small feat). So, it is right side up which allows me to do the tabbing of the running surface internals to the frame members.
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In discussing the tabbing, the Naval Architect mentioned that I could use either 'peanut butter' or triangular shaped foam as the fillets. OK . . . foam it is.
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Hopefully, I'll finish this up today.

With the extension bracket right-side up, I have a nice surface to lay-out and cut the fiberglass. Here are the rolls of 1808 & 1708.
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On another front . . .

The Admiral was not satisfied with one bathroom make-over . . .
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So, she is onto the next one. . .
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I had to do all the tile cuts on the other bathroom, but I think she will try doing the cuts on this bathroom.

 

[tphoyt]

I’m sure the foam was a time saver.
That worked out well.

 

[Pmt133]

I like the foam. When I did my stringers and deck I just tabbed them in in one shot when the edge was bedded in PB so it was a wet tab on the wet PB and the roller made the filet. Obviously it's unrealistic to have done that for you project. In the spots I didn't do that foam would be much easier.

I like the flooring in the bathroom too. Tile to the molding is a cleaner look (or is the trim just resting before tiling? I've seen both ways.)

 

[tpenfield]

I'm getting close to completing the internal tabbing and related work on the inside of the planing surface. One thing that I had planned was to have some gussets tied to the stringers.

The Naval Architect (NA) said that I did not really need the gussets, but I had already cut and shaped the core pieces, so I am proceeding with the gussets. I did take out some of the gussets on the top of the stringers, because I needed to run some extra layers of glass, based on the input from the N.A.

Anyway, I figured for the running surface a little extra support would be a good thing, considering any impact (slamming) forces that the boat might encounter.

So, here are the gusset cores just put in place. I glassed a few of them yesterday just to see how they set up. Looks OK, and I'll do the rest of them today. Once they are all installed, I'll drill a small drainage hole in the base of them to let any bilge water go fore/aft as needed.
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I was thinking of tying them together to form ribs . . . Maybe.

 

[tpenfield]

More progress . . .

I got the gussets installed . . .
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Then I went on to the 'bottom plate' of the bracket portion. . .
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I did traditional fillet for this tabbing rather than the angle-cut foam. This is the first layer of tabbing (1708). It will get an 1808 layer and then another 1708.

I am concerned about the portion of the engine stringer where it meets both the back wall of the planing surface and the 'lateral brace' (Red Arrow). I think I need something a little more solid there to absorb/distribute impact forces from slamming. I added some laminations, but it does not seem like enough.

I probably should have made that area a solid portion of the stringer, but I cannot exactly remember the thinking at the time. I'll add a piece of Coosa and glass it in with a couple layers of 1808.

Anyway . . . 3 more pieces to go . . . the transom and the 2 splash wells