Trouble free transmissions – arent we lucky!

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    Having just survived a gearbox transplant, I thought I would check the forum to see how many people had discussed transmission, clutch and drive problems…. the answer…. none!

    Unfortunately, Voltair was not so lucky in June, when Robin returned from Morocco to Gibraltar admitting that “the drive in forward gear doesn’t seem to take up quite like it used to”. In fact, it was slipping so badly that the oil in the TMP box had seriously overheated, and another few hours would probably have seen total loss of forward drive (reverse was fine, but not much help when butting into a force 7).

    TMP in Weybridge did a terrific job in reconditioning our spare gearbox, and TNT did well to get it from Surrey to Malaga in 3 days, on their economy service. I drove from Gib to Malaga to pick it up, and with the services of an engineer from Sheppards Boatyard we were up and running again in 8 days.

    So if anyone wants to ask about how to lift a Perkins 4-108 engine and transmission without taking the boat out of the water, how to separate engine and gearbox and how to put it all back together again, we might be able to help!

    Also, if anyone has a knackered box and needs a spare for reconditioning, we have one you could buy …. the snag is, it’s strapped to Voltairs side deck by the shrouds and she is halfway back to Lisbon as I write. The plan will be to go fetch it and some other stuff from Portugal during the winter.

    Ronar M

    Hi All

    I have also done this job on Ronar M with the boat in the water. It took about 3 hours to get the box out one Good Friday. I ran it up to TMP on the Saturday from Plymouth. It was reconditioned and rebuilt over the Easter weekend and I picked it up the following Tuesday. Great service. It was back in the boat and undergoing trials by Wednesday afternoon. It is a very heavy piece of kit and has to come off with the bell housing which also has the after engine mounts attached. I put a beam across the cockpit locker tops and used a 4;1 tackle with the fall going on to a primary winch to lift the after end of the engine. I then slipped a piece of timber under the engine sump to support it while the gearbox and bell housing were out of the boat. One word of warning; I got the gearbox back from TMP and didn’t bother to paint it before it went back in. I wish I had. Cheers, Trevor


    I have been trying to reach Thamesway Marine Products. I have called and faxed the number on their website. I tried emailing the address on their website without a response. Would you have any current contact information? I’m interested in locating the rubber coupling between the output flange from my TMP MK IV 12000 gearbox. The diameter of the shaft is 1″3/8. I own CN 38 hull 123
    thanks for your response
    George Nauman

    Ronar M

    Hi George

    The number I have is 01932 843072. After 9am (it’s 0810 now) I will try calling this and see what happens. Will get back to you. Trevor

    Ronar M

    Hi George,

    I too cannot get through. I am getting a fax noise – I guess this number is a telephone and fax machine combined. Maybe the company is closed for the holidays? Maybe you will get a reply to your fax when the holidays are over. As far as I gathered when I had my gearbox fixed the company is a one man band so when he’s on holiday there’s no one else to respond to calls. Cheers, Trevor
    Cheers, Trevor


    Thanks for your response. You brought good news that TMP was in business in late July of this year. With luck he will find my fax on the floor in front of the machine and envelope in the post when he returns.

    Czarina Blue

    I have recently suffered intermittent loss of forwards propulsion simultaneous with the Perkins 4108 hunting up 100 revs. This cycle occurs about once a minute for 15 secs, and I see my hull speed drop off during the higher revs. The prop shaft is still turning during that time but I imagine that is from the force of flow over the prop blades?

    Spoke to Kevin from THamesway Marine this morning and he says the bearing will be worn and the Gearbix a Thamesway 12000, probably a Mark II, will need to come out and be overhauled. This will cost around £1200 inc VAT and parts, with the courier charges on top, and it’s a heavy item.

    Unfortunately I am in Sicily, in Siracusa, and not expecting this (!) I am now looking for a mechanic / engineer to help with this. I understand from the forum that this may be possible with the boat in the water, as Voltair and Trevor have managed it in the past.

    Just wondering if this box is worth overhauling bearing in mind its age and the difficulty of getting parts apart from via the UK, or there is any advantage in considering a more modern adaptation? From the forum it sounds as if people have stuck with the old box, and just renovated it.

    Any further advice on its removal and or replacement with more modern versions, I would much appreciate.




    To reply to Duncan’s request, please use topic here.

    Marilyn, moderator

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