Remodeling engine bed - advice needed

[arecuk]

guys,

Im swaping old volvo penta 2002 for perkins 103.06 18hp and i need to adjust engine bed and position of engine mounts

OLD SITUATION
- the front part on engine bed for volvo was cut off, see picture, and this part i need to remodel
- also, the bed is from fiberglas and on top of it are stripes from metal with welded nuts for engine mounts; the whole thing is cover again with couple of layers of fiberglas and gelcoat

WHAT I DID
- i remodeled the front part from fiberglas, cloth plus resin; i kept the original bolts in place; compare both images

PLAN?
- grind down the new fiberglas blocks, on top of it place new metal stripes with welded nuts in right positios for new mounts; then cover it with layers of fiberglas; the metal stripe i would screw on with 3 long bolts, reaching down the original fiberglas bed
1) would it be strong enough?

2) i dont know what to do with rare mounts as i cant use the nuts from original mounts due to difference in old and new mounts; so i plan to use only one original welded nut and for the second screw i would drill a new hole (but i cand weld the nut here)

All ideas welcome thanks, tomas

[arecuk]

Image1

[arecuk]

Image2

[arecuk]

Image3

[model 10]

Is it to late to make a 1 piece mount bed for each side?

[Lepke]

You have to transfer the thrust of the engine to the hull and the hold down screws also have to resist the loosening effect of vibration. Usually some type of beam is glassed in. To me, an old guy, it looks like you have wood beams under the glass. I would run stainless lag bolts in a pre-drilled hole. When you drive the lag, pour some epoxy into the hole to lubricate the lag and help the long term holding power of the lags. It also helps with the vibration the lags absorb. Do your glassing with epoxy resin. Sand well where you bond to the existing fiberglass.

[arecuk]

Thanks guys! Actualy what i think of is that i would remove the original and party rusted glassed- in metal stripes on top of the bed where original mounts were attached to.

Then, i would put in place new stainless stripe covering both parts of the engine bed - the original rare part and the new front part i built. I would screew it with couple of big bolts to the fiberglass bed. I would pour some resin in the holes before screewing. Then i would cover it again with few layers of fiberglas.

Im just worried about structural integrity of the new fiberglass blocks i made. I used cloth, sanded well surface contacts. It looks very strong and solid but still, it is piece of fiberglass ...

[reed1v]

Ideally you would cut out the old bed, buy a new one sized to your engine and install that with new glass. The bed is the only thing keeping the engine in place. Lots of stress on the engine as it runs into seaways. Usually the bolt holes are sized a bit small to really hold down the engine as it vibrates. Old holes are not going to be tight. Also be sure your engine mounts are sized to the engine. Good luck.

[Oceandeep]

I've only rebuilt my engine bed once and that was in my last boat a 35 Yorktown with a Perkins 4108. The Yard advised me to make the bed out of heavy 4 X 4 Hardwood and then fiberglass it in place. I then bolted new motor mounts in place with big lag screws that went deep into the underlying hardwood frame. The solution worked out well and I got several years of trouble free service from it before I sold it.
So my suggestions would be similar to Lepke's... I would remove all of the old metal pieces from the last installation. Make sure that the bed is "well fiber glassed" into place. I can't see the detail very well in your pictures but you might need to add some fiberglass fillets on the edges to ensure that the bed is well attached to the hull with an adhesive like West System 403 and then add additional layers of cloth as needed. Make sure that you prepare the surfaces well by sanding and cleaning with acetone so that the new glass will bond well. Once you are convinced that the bed is strong and well attached to the hull then I would temporarily install the new motor and determine where to place the new motor mounts and install using the "lag bolt and epoxy approach" previously described. Best of luck

[jimbunyard]

It seems to me that you're adding a layer of complexity that may in the end make the alignment of the engine difficult.

The fiberglass blocks you've added should be sufficient to hold the engine, there is no real need for any metal plates to fasten the motor mounts to. Fasten the engine mounts directly to the fiberglass blocks.

You should however glass the blocks you've added to the existing engine bed; the laminating resin or putty alone might be adequate, but it's better to have multiple methods of bonding in this critical area.

Since you have solid fiberglass rather than wood to screw/bolt to, there are a couple of issues. If you use lag screws to secure the mounts or plates (whichever you decide) then you must make the proper size pilot hole, or you'll break the screws (too small), or the screw won't hold (too big). If you use machine bolts, then you should drill an oversize hole, fill it with an epoxy/milled fiber putty, and set waxed or lightly oiled bolts in that, using the mounts as a template. Conversely, you can drill the oversize holes, fill them with putty, and drill and tap them after the epoxy hardens.

Since you have a pretty tight engine compartment, and I don't imagine you want to keep setting the engine in and out to check that everything fits, it might be advantageous to make a template of your engine and transmission. That is, using 2x4s and plywood, build a model that duplicates the location of all four engine mounts and transmission output flange and angle, and use that to aid in fitting the engine. You can also use it to check various other aspects of the fit, such as accessibility for maintenance.

[arecuk]

Guys, your advices are very helpfull, especialy down here in guatemala where one must improvize. Also my budget is tight.

So what i did - removed the old plates, grinded the thing to fit the new plates. I would rather have the steel plate for mounts, rather then mount them directly to fiberglass bed. See picture, i thing its going well so far.

Regarding engine mounts - the only ones i can get here are bushings df-100. I hope its fine for my small perkins.

[reed1v]

Man, just stop screwing around with it and have a yard make you an engine bed configured to your engine.Unless done correctly, you are goingto have problems aligning shaft to transmission, and to the prop; you also risk having the engine rip apart the bed slowly but surely. You do not want an engine bouncing around down below or suddenly loosing your stuffing box.

[ramblinrod]

Originally Posted by arecuk

guys,

Im swaping old volvo penta 2002 for perkins 103.06 18hp and i need to adjust engine bed and position of engine mounts

OLD SITUATION
- the front part on engine bed for volvo was cut off, see picture, and this part i need to remodel
- also, the bed is from fiberglas and on top of it are stripes from metal with welded nuts for engine mounts; the whole thing is cover again with couple of layers of fiberglas and gelcoat

WHAT I DID
- i remodeled the front part from fiberglas, cloth plus resin; i kept the original bolts in place; compare both images

PLAN?
- grind down the new fiberglas blocks, on top of it place new metal stripes with welded nuts in right positios for new mounts; then cover it with layers of fiberglas; the metal stripe i would screw on with 3 long bolts, reaching down the original fiberglas bed
1) would it be strong enough?

2) i dont know what to do with rare mounts as i cant use the nuts from original mounts due to difference in old and new mounts; so i plan to use only one original welded nut and for the second screw i would drill a new hole (but i cand weld the nut here)

All ideas welcome thanks, tomas

I can't really tell from your pictures what you have or need.

As long as the existing beds are good (no moisture ingress) I re-use them rather than replace them.

1. If engine mounts fit on existing beds. Fill old holes and drill new ones for fastening mounts to beds with lag bolts. (To seal the wood core, I turn out the lags, pour in low viscosity epoxy and after an hour or so, remove excess epoxy, and turn the lags back in.)

2. If engine mounts don't fit existing beds, I fabricate angle iron brackets to suit. Bolt them into the beds and bolt the mounts to them.

[motion30]

I . always thought large 1/2" thick aluminum a angle iron would be much simpler and would never rot. am I missing something? That is what is U in the offshore racing power boats

[reed1v]

1. would advice against gluing(epoxy) the lags into the bed. Down the road you will want to remove the engine and may not want to destroy the bed in doing so.
2. Nothing wrong with aluminium except its a soft metal. The racing boats are not built to last very long. Also aluminum needs protection against corrosion due to stray currents, galvanic reactions, and certain chemicals. That said, makes a fine hull as long as you stay away from currents which can disintegrate aluminium quickly. It basically becomes an zinc anode. It also can get stress cracks(think airplane wings) from repeated flexing. Doubt if that would be relevant to your situation.