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Phil
Jan 25, 2010 - 1:22PM
Engine mount questions and bits and bobs
Hi Everyone,
Looking to re-engine Tresco Maid this spring and wonder if anyone can help with the following:
1- I wonder does anyone have drawings that indicate the position of the engine mounts in relation to the prop shaft orientation and associated dimensions?
2- What do the original mounts bolt into i.e. what is beyond the fibreglass bearers? steel, wood etc.
The existing 4107 was rebuilt in 2001. It runs well but I would like something that will assure me of reliable running in the med... The engine will be out in april/may. Amongst other things tt has a recon starter (date unknown) and i replaced the alternator with a new (not recon) in 2009..... Anyone that may be interested in all or bits can contact me at philsomerville@hotmail.com
Best Regards
Phil
PS Thanks John for the advice on engines etc....
SeaDog Name (if owner or crew) Tresco Maid
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E Richardson
Jan 25, 2010 - 1:41PM
Re: Engine mount questions and bits and bobs
Hi Phill
I do not have such a drawing, but the engine mounts fasten into timber bearers. The bearers are encapsulated by the fibre glass you can see. Each engine mount is fastened down by two seperate systems. At one end of the mount is a simple square headed coach screw. The other end is bolted down to a piece of round bar which passes through the timber bearer a few inches below it's upper level.
If I was re engining a Seadog I should fit a Beta Marine engine as In John and Grahams boat. Its a Kubota engine and spares are readily available in most countries as it is the engine used in most mini diggers-small dump trucks etc. For this reason they are often cheaper than the likes of Yanmar etc.
I assume you have the short section of prop shaft between your gearbox and the final drive shaft. This is a better arrangement than a one piece shaft so don't be tempted to change the system even if you renew your shaft.
The Beta engine is a more compact unit than the Perkins, my preference is for the hydraulic gearbox. It is slightly more expensive than the standard unit. However Beta Marine will fit your Borg Warner box to their engine and that is the best gearbox made but it takes up a bit more room.
Happy to discus it if you wish.
Eric
SeaDog Name (if owner or crew) Ex Taliesin
Steve Abbott
Jan 25, 2010 - 2:59PM
Re: Engine mount questions and bits and bobs
Hi
Whilst accepting that the Baeta engine as recommended by Eric, Graham et al is probably the ideal Perkins replacement for a Seadog, you should be aware that in the Med such things are unknown by boatyard mechanics, and spares not readily available (I know that you can get many items from industrila machinery suppliers, but think of the problems of finding them in a foreign country, with the language difficulty).
Consequently, we opted for the 30hp Yanmar unit (the most popular marine engine brand in the world, after all), since Volvo & Yanmar are the universal engines in the Med area, and consequently the spares are available, and more importantly, every mechanic in a boatyard or marina will know how to maintain & fix it.
Although a more costly option, and at 30hp, less powerful than the Beta unit (we cruise at around 5 - 5.5 knots and get about 6.2 - 6.5 knots flat out), we feel that the consequent peace of mind was well worth it, and we've been very pleased with it to-date (although it's only been a few months).
SeaDog Name (if owner or crew) Arethusa
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Phil
Jan 25, 2010 - 3:06PM
Re: Engine mount questions and bits and bobs
Hi Eric,
Thanks for the detailed reply...
I have extensive experience of the beta and agree with you.
I'm a little puzzled by the dual shaft with the two universal joint type couplings (one at the putput and one mid point). The ones on Tressy are pretty much shot and I was thinking of replacing the setup with a single shaft and a centreflex coupling on the gearbox output. However, I'm interested in keeping the arrangement if you think that it's a good idea but would need to replace the joints (well at the very least the rubbers). Any further thoughts/advice welcomed.
Thanks for your help...
Phil
SeaDog Name (if owner or crew) Tresco Maid
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Graham
Jan 25, 2010 - 4:11PM
Re: Engine mount questions and bits and bobs
Hi Phil,
I was very glad that I retained the separate shaft on Dougal when we re-engined a few years ago. After we launched we found that the folding propeller was incorrect and had to be removed. By disconnecting the flexible joints I was able to remove the propeller and change it without removing either the engine or the rudder. If we had used a single shaft then one or the other would need to be shifted so that the shaft could slide forwards to remove the propeller. This may not be needed if you have a fixed propeller and do not have a rope cutter.
I was thankful again at the start of last season when I had to change the propeller again.
Scotty from TS Marine had originally tried to persuade me to change to a single shaft and a new gearbox but after the job was completed he had changed his mind and said that he would be recommending Dougal's setup to any other SeaDogs he spoke to.
By the way his approach to the engine alignment was to lower the new engine in by crane then make up suitable mild steel brackets to suit. The gearbox position of course remained the same so only the front brackets needed to be fabricated.
Graham
SeaDog Name (if owner or crew) Dougal
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Phil
Jan 25, 2010 - 5:15PM
Re: Engine mount questions and bits and bobs
Thanks for the input :-)... I also intend to go for a 30 horse but dispite your very valid points, will probably stick with the beta... economics and my existing knowledge of beta makes me lean towards them I think...
SeaDog Name (if owner or crew) Tresco Maid
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Phil
Jan 25, 2010 - 5:26PM
Re: Engine mount questions and bits and bobs
Hi Graham, thanks for your reply...
I may be wrong but I'm not mad on keeping the gearbox.. I know they have a great reputation but mine is leaking quite a lot and I'm not sure it's worth the bother of overhaul. In my experience overhauling is never as sure a process as original manufacture and I'm trying to achieve, within reason, a fit and forget installation. I have experience of the mechanical PRM 120 though and I've found them bullet proof and very easy to pull to bits...
Thanks again Phil
Any input on the flexible couplings / universal type joints from anyone would be welcome, including the replacement of the rubbers...
SeaDog Name (if owner or crew) Tresco Maid
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E Richardson
Jan 25, 2010 - 10:28PM
Re: Engine mount questions and bits and bobs
Hi Phill
If memory serves right I believe they were made by Silentbloc and I believe they are still in existance. If you have a problem I may be able to trace where I have obtained them from. Having done all the calcs on engine size Reg Freeman had it just about spot on with the Perkins. Re the PRM gearboxes I often recomend them to friends, although where they can afford it the PRM hydraulic box is best choice. It will take more high speed changes done in panic and I am an expert on the done in panic bit in Dutch locks.
The reasons for recommending the two piece shaft arrangement is exactly what Graham says. As an example you can remove the prop or change a cutlas bearing all with out removing the engine or rudder. The beta engine is also much cheaper not only to buy initialy but also to relace if ever you need to. Just buy the industrial unit and swop all the marinisation kit. The Yanmar unit is excellent but costly.
If you do decide to go for a Beta please give me a ring as there are a few points worth being aware of.
Eric
SeaDog Name (if owner or crew) Ex Taliesin
John Lansdell
Jan 26, 2010 - 4:27PM
Re: Engine mount questions and bits and bobs
Hi! Re the engine bearers. On Twotails there were 8 coach bolts vertically into the encapsulated wood. Of the 8 only 3 were effectively holding the engine in place, as either the wood had gone soft, or the bolt had rusted away. When we bought her she had been flooded with fresh water and this must have caused some of the problem. As a result she now has an L section steel "RSJ" cut to fit above and alongside the original bearers, and heavily galvanised, held in place with 3 horizontal bolts and 2 vertical coach bolts into good wood on each side. The logic was not only to ensure the strength of the bearers, but also to stiffen them such that the mounting blocks did more work to keep vibration and noise out of the boat. The mounting blocks are retained onto the steel by set bolts with spring washers screwed into tapped holes in the RSJ.
We fitted a Beta, with the original BW gearbox, which means the engine centreline and gearbox output were inline with each other. Other gearboxes may have the output shaft not coincident with the engine.
Tip from a boatyard mechanic! Sorry Phil, but others may not know this one. As soon as you get the engine, put the rubber mountings onto it and allow them to settle in place while you do the other preparatory work.
As regards alignment, with the prop shaft out it is possible to identify a place on the forward bulkhead (using a Mk 1 eyeball) to which an alignment cord can be attached, and also at the centre of the stern tube. Then make a wooden engine mockup from 4 bits of softwood to replicate the centre line of the engine, and also its bearers. In my case the centre line markers were two long woodscrews, allowing easy adjustment during its build. The rubber engine mounts can then be put on the mockup and their height adjusted in situ to suit the cord. The mounts are then in place to mark out where to drill and tap the holding down bolts. Replace the mounts and you are ready to drop the engine in.
So far as I can remember the alignment and swash between gearbox and propshaft was within 1mm when the engine was put in. This can easily be absorbed by the split prop shaft.
SeaDog Name (if owner or crew) Twotails
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Philip Ellis
Jan 27, 2010 - 5:04PM
Re: Engine mount questions and bits and bobs
Hi Phil,
I have just had the engine out and recently reinstalled after replacing engine mounts.
At the same time I replaced the flexible coupling rubbers with like for like.
The are available redily from ASAP supplies and Golden arrow Marine.
The Front and Rear oil seals were replaced in the BW gearbox along with the drive plate again all these spares are available from ASAP supplies.
I have all the dimentional data for the engine mount positions and down angle aif you want it.
I made an aluminium jig for the engine mounting positions which alighed with a laser located in the cutlass bearing housig to project the centre line.
Is your boat in Falmouth still?
As that is where I am located and could give you all the gen if you wish.
Regards
Philip
SeaDog Name (if owner or crew) Glyfada, ex Natuna
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Phil
Jan 27, 2010 - 5:56PM
Re: Engine mount questions and bits and bobs
Thanks John, I will be looking to do something similar with the bearers.... thanks again for your help
SeaDog Name (if owner or crew) Tresco Maid
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Phil
Jan 27, 2010 - 6:00PM
Re: Engine mount questions and bits and bobs
Hi Glyfada,
Thanks for your response... I would like the info you have. It would be very helpful. Tressy is out of the water at the moment in QAB Plymouth but will be back in Falmouth for the summer I hope..I don't have your contact details but if you could text me I could call you back at a convenient time. My number is 07908 115112
Best Regards
Phil
SeaDog Name (if owner or crew) Tresco Maid
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E Richardson
Jan 28, 2010 - 9:28AM
Re: Engine mount questions and bits and bobs
Hi Phill
I note that you say you are going for 30hp. The engine you need is actually 35bhp at 2800 rpm or 38 at 3600 rpm. They are the same basic engine just a different fueling set up so the size is the same. The 28hp would be a bit to small. I would opt for the 38hp. I will do the Calcs latter and put them on the forum.
Whilst a smaller engine will push the Seadog ok, it will struggle against a strong tide. It is better to be just above your needs than short of power when you need that extra push. It is also easier on the engine than having to run flat out when going against strong winds or tides.
Eric
SeaDog Name (if owner or crew) Ex Taliesin
Graham
Jan 28, 2010 - 9:36AM
Re: Engine mount questions and bits and bobs
I remember you posting this previously Eric. The following should be a direct link to your calculation.
http://www.seadog.org.uk/forum.htm#bn-f … 51447/show
posted in 2007
SeaDog Name (if owner or crew) Dougal
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Graham
Jan 28, 2010 - 9:38AM
Re: Engine mount questions and bits and bobs
Looks like the link isn't 'clickaple' but if you copy and paste the entry it should work.
SeaDog Name (if owner or crew) Dougal
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Graham
Jan 28, 2010 - 11:39AM
Re: Engine mount questions and bits and bobs
Just been looking at the current engine range on the betamarine site and I admit I am quite confused. The engine we have is the BV1505 which was rated at 37BHP but I cannot work out the equivalent model.
http://www.betamarine.co.uk/Templates/sea_going.html
SeaDog Name (if owner or crew) Dougal
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E Richardson
Jan 28, 2010 - 2:37PM
Re: Engine mount questions and bits and bobs
Hi Graham and Phill
The old 1505 engine is now the engine used as either 35hp at 2800 Rpm or 38hp at 3600 Rpm depending on the fueling settings. The pervious 35hp was actually a 1300cc unit which is no longer used.
Not sure how to cut and paste the old article Graham.
Rough calcs below give some idea of the prop sizes needed with different hp engines and max theoretical hull speeds, you will always get a bit less due to drag with the extra wetted area of the bilge keels.
The Standard (if there is one) prop for a Seadog is 17x12
28hp Speed 7.2 Knots Prop 15.5x12
35hp Speed 7.7 knots Prop 16.3x12
38hp Speed 7.8 Knots Prop 17x12
These calcs seem to be quite variable depending whose formula you use, but I believe the bigger engine is best. As it spends a lot more time running at lower throttle opening rather than pushing the smaller unit.
Eric
SeaDog Name (if owner or crew) Ex Taliesin
Phil
Jan 29, 2010 - 9:15AM
Re: Engine mount questions and bits and bobs
Thanks for all the input everyone... It seems the silent bloc couplings have become obsolete. I've spoken with the manufacturer and they would want an order for a minimum of 50 units to make a production run worth their while.... I'm wondering whether to substitute them with split half couplings and R&D couplings.... Does anyone know the seadogs shaft size off hand (It's a pain trying to organise things at arms length but I don't want to loose half the season if i can help it).
Regarding engine size.... all points noted... i just feel that the seadog is a little over-engined for my liking. I think I would prefer to run a smaller engine at a higher percentage of its output and benefit from the space saving it would offer... we'll see :-)
Any thoughts reference the shaft couplings would be welcome....
Phil
SeaDog Name (if owner or crew) Tresco Maid
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Philip Ellis
Jan 29, 2010 - 9:26AM
Re: Engine mount questions and bits and bobs
Hi Phil,
The original tail shaft size is 1 1/4 inch imperial.
Regards
Philip
SeaDog Name (if owner or crew) Glyfada, ex Natuna
E Richardson
Jan 29, 2010 - 4:21PM
Re: Engine mount questions and bits and bobs
Hi Phill
It is quite possible that R & D have a suitable coupling in their range. Unfortunately I cannot remember the Pitch Circle Diameter to look it up. Have you tried Golden Arrow Marine, they may still have a stock.
Eric
SeaDog Name (if owner or crew) Ex Taliesin
Phil
Jan 29, 2010 - 4:49PM
Re: Engine mount questions and bits and bobs
Seems there may be a result on the coupling.... I contacted T Norris on Phil Ellis's and Eric's suggestion. Jonathan there, who mentioned someone else had been in contact with him, told me R&D have agreed to make a suitable substitute that will fit the original spiders. They will be in stock next week. I'm working nearby so will pick a couple up and see how they measure up..... I'll report back...I did check with Golden Arrow Eric but it seemed they had none left... BIG thanks Chaps :-)...
SeaDog Name (if owner or crew) Tresco Maid
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Philip Ellis
Jan 29, 2010 - 9:32PM
Re: Engine mount questions and bits and bobs
I had discussusion earlier today with both T.Norris and later with Roger at R&D marine. This with a view to arriving at a reliable source of a direct replacement for the no longer manufactured Silentbloc flexible coupling element.
Lancing marine had earlier suggested that part ref 910-060 would work as a replacement, however, this I recognised as an R&D part No, so I asked Roger at R&D to confirm that this part would indeed be a direct replacement, as it is listed as a fit for the TMP gearbox and not the Borg Warner. However after convincing him that the Borg Warner fitted to Seadogs had a two bolt adapter that fitted directly to the Silentbloc FC9218 with its 3 3/16 inch PCD and 7/16 unf bolts then he said that it should. But he would like to confirm this. The other dimensions and torque capacities for 4108 with 2:1 reduction look as though they are in spec too.
So subject to final confirmation from R&D and Phil( Tresco Maid) fitting them sucessfully then we may have an improved and continuous source of replacement couplings.
I will send R&D some photgraphs of the BW output arrangment as he has never seen a two bolt adapter fitted to this box! and that in his 30 year experiance. If I can find an old FC9218 I will send that too, that will then confirm the installed distance.
Once the R&D part No is confirmed then these could be ordered either the usual suppliers who list R&D parts eg. T.Norris, Lancing Marine, etc or direct from R&D.
Perhaps Phil(TM)will update this thread as he progresses.
Lets hope this has a sucessful outcome.
Philip Ellis
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